Vulcanizable liquid compositions

ABSTRACT

There is disclosed a linear block copolymer comprising at least one triblock I-B-I, wherein I is a block of at least one polymerized conjugated diene of at least five (5) carbon atoms, such as isoprene, and B is a block of a polymer of at least one conjugated diene, different from that used to polymerize the block I, of at least four (4) carbon atoms, such as 1,3-butadiene. The B block is selectively hydrogenated, while each of the I blocks is unhydrogenated and therefore retains a sufficient amount of its original unsaturation to vulcanize the copolymer. There is also disclosed an alternative linear block copolymer containing at least one triblock of the first polymer block made from a minor proportion of at least one aryl-substituted olefin, such as styrene, and a major proportion of at least one conjugated diene used to polymerize the block I, the second middle polymer block of at least one diene used to polymerize the block B, and the third polymer block which is the same as the first polymer block. In this alternative copolymer, the middle block is also selectively hydrogenated, thereby leaving the terminal polymer blocks with a sufficient amount of their original unsaturation to vulcanize the copolymer. The polymers can be crosslinked or functionalized through the terminal blocks containing the vinyl unsaturation. There are also disclosed random linear and star-branched block and random copolymers made from the same monomers at the linear block copolymers. 
     Also disclosed are methods of producing the polymers and selectively hydrogenating the aforementioned polymerized dienes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related by subject matter to application Ser. No.07/466,233, filed on Jan. 16, 1990 and to application Ser. No.07/466,136, filed on Jan. 16, 1990.

The entire contents of application Ser. No. 07/466,136 are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is directed to novel liquid block copolymers havingunsaturation only on the terminal blocks and methods of preparationthereof. More particularly, the invention is directed to liquid blockcopolymers comprising triblock units wherein the middle block of eachtriblock unit is substantially selectively hydrogenated and thereforecontains substantially no unsaturated groups, while each of the terminalblocks of each triblock unit contains a sufficient amount ofunsaturation for curing the block copolymers.

The invention is also directed to random liquid copolymers which, whenselectively hydrogenated, contain molecules having substantiallysaturated backbones and random, pendant unsaturation.

The invention is additionally directed to chemically modifiedderivatives of the above block and random copolymers.

Crosslinking of the polymers of the invention produces elastomericvulcanizates having unusual properties, e.g., high elongation andexcellent aging characteristics.

2. Description of Related Art

Elastomers (or rubbers) of either natural or synthetic origin usuallyrequire vulcanization for transformation into insoluble, high strengthelastomeric products. Before vulcanization, rubbers possess inferiorproperties and low strength which limit their utility.

There are a number of well known methods for achieving thevulcanization, also referred to as crosslinking, of unsaturatedelastomers. Such methods include the use of sulfur and accelerators,peroxides, benzoquinone dioxime, certain phenolic resins and similaragents. Any of the above or any other well known vulcanizing techniquesmay be utilized to crosslink the elastomers of this invention.

Liquid elastomers are well known and are used in various applications.For example, many functionally terminated polybutadiene liquidelastomers are known. These materials are generally highly unsaturatedand frequently form the base polymer for polyurethane formulations. Thepreparation and application of hydroxy-terminated polybutadiene isdetailed by J. C. Brosse et al in HYDROXYL-TERMINATED POLYMERS OBTAINEDBY FREE RADICAL POLYMERIZATION-SYNTHESIS, CHARACTERIZATION ANDAPPLICATIONS, ADVANCES IN POLYMER SCIENCE 81, Springer-Verlag, BerlinHeidelberg, 1987, pp 167-220.

Also, liquid polymers possessing acrylate, carboxy - ormercapto-terminals are known. In addition to butadiene, it is known toutilize isoprene as the base monomer for the liquid elastomers. Theliquid elastomers may contain additional monomers, such as styrene oracrylonitrile, for controlling compatibility in blends with polarmaterials, such as epoxy resins.

Also known in the prior art are pure hydrocarbon, non-functionalizedliquid rubbers. These liquid elastomers contain varying degrees ofunsaturation for utilization in vulcanization. Typical of highlyunsaturated liquid elastomers is polybutadiene, e.g., that sold underthe name RICON by Colorado Chemical Specialties Co. A liquidpolyisoprene which has been hydrogenated to saturate 90% of its originaldouble bonds is marketed as LIR-290 by Kuraray Isoprene Chemical Co.Ltd. Still more highly saturated are liquid butyl rubbers available fromHardman Rubber Co., and Trilene, a liquid ethylene-propylene-dienerubber (EPDM) from Uniroyal Chemical Co. The more highly saturatedliquid elastomers exhibit good oxidation and ozone resistant properties.The above prior art liquid elastomers, with either high or low levels ofunsaturation, are characterized in that, having random unsaturation,they are randomly crosslinked during vulcanization. The success ofvulcanization in incorporating all molecular chains into the finalcrosslinked network with minimal "loose ends" is termed the degree ofnetwork perfection. An imperfect network, wherein crosslinks occurrandomly and sometimes not near the end of a molecular chain, produces avulcanized polymer having poor mechanical and elastomeric propertiescaused by chain ends which are not a part of the tightly bound network.In order to insure the highest degree of network perfection attainable,randomly unsaturated elastomers must be crosslinked extensively. Thelarge number of crosslinks necessary dictates that the average distancebetween crosslinks (M_(c)) must be relatively small in comparison withthe dimensions of the whole molecule. Elastomeric properties, such aselongation, depend greatly on M_(c) --the smaller the M_(c) the worseare the elastomeric properties, e.g., the lower the elongation of thepolymer.

Falk, JOURNAL OF POLYMER SCIENCE: PART A-l, Volume 9, 2617-2623 (1971),the entire contents of which are incorporated herein by reference,discloses a method of selectively hydrogenating 1,4,-polybutadiene inthe presence of 1,4-polyisoprene. More particularly, Falk disclosesselective hydrogenation of the 1,4-polybutadiene block segment in theblock copolymer of 1,4-polybutadiene-1,4-polyisoprene-1,4-polybutadieneand in random copolymers of butadiene and isoprene, with bothpolymerized monomers having predominantly 1,4-microstructure. Selectivehydrogenation is conducted in the presence of hydrogen and a catalystmade by the reaction of organoaluminum or lithium compounds withtransition metal salts of 2-ethylhexanoic acid.

Falk, DIE ANGEWANDTE CHEMIE 21 (1972) 17-23 (No. 286), the entirecontents of which are also incorporated herein by reference, disclosesthe selective hydrogenation of 1,4-polybutadiene segments in a blockcopolymer of 1,4-polybutadiene-1,4-polyisoprene-1,4-polybutadiene.

Hoxmeier, Published European Patent Application 88202449.0, filed onNov. 2, 1988, Publication Number 0 315 280, published on May 10, 1989,discloses a method of selectively hydrogenating a polymer made from atleast two different conjugated diolefins. One of the two diolefins ismore substituted in the 2,3 and/or 4 carbon atoms than the otherdiolefin and produces tri- or tetra-substituted double bond afterpolymerization. The selective hydrogenation is conducted under suchconditions as to hydrogenate the ethylenic unsaturation incorporatedinto the polymer from the lesser substituted conjugated diolefin, whileleaving unsaturated at least a portion of the tri- or tetra-substitutedunsaturation incorporated into the polymer by the more substitutedconjugated diolefin.

Mohajer et al, Hydrogenated Linear Block Copolymers of Butadiene andIsoprene: Effects of Variation of Composition and Sequence Architectureon Properties, 23 POLYMER 1523-1535 (September 1982) discloseessentially completely hydrogenated butadiene-isoprene-butadiene (HBIB),HIBI and HBI block copolymers in which butadiene has predominantly1,4-microstructure.

Kuraray K K, Japanese published patent application Number JP-328 729,filed on Dec. 12, 1987, published on Jul. 4, 1989, discloses a resincomposition comprising 70-99% wt. of a polyolefin (preferablypolyethylene or polypropylene) and 1-30% wt. of a copolymer obtained byhydrogenation of at least 50% of unsaturated bond of isoprene/butadienecopolymer.

Heretofore, the art has failed to produce liquid hydrocarbon elastomershaving the capability of maintaining relatively large distance betweencross-links (high M_(c)) after vulcanization.

Accordingly, it is an object of this invention to provide liquidpolymers capable of being vulcanized to a substantially perfect networkwith a distance between crosslinks nearly equivalent to the dimensionsof the unvulcanized elastomeric molecule. In addition to the expectedimprovements in elastomeric properties, the unperturbed saturated mainchain of the polymers of this invention provides a high degree ofoxidative and thermal stability. Unique materials can also be obtainedby chemical modification of the polymers of this invention since thepolymers of the invention can be selectively modified at the terminalends of the molecules.

It is an additional object of this invention to provide a method for theproduction of random copolymers having controlled amounts ofunsaturation incorporated randomly in an otherwise saturated backbone.In contrast to EPDM, the level of unsaturation can be inexpensively andeasily controlled, e.g., from 1% to 50%, to provide a wide variation invulcanization rate and potential co-curability with various highlyunsaturated rubbers based on butadiene or isoprene.

SUMMARY OF THE INVENTION

In one embodiment of the invention, there is provided a liquid blockcopolymer comprising at least three alternating blocks:

    (I).sub.x -(B).sub.y -(I).sub.x

wherein I is a block of at least one polymerized conjugated diene havingat least five (5) carbon atoms and the following formula ##STR1##wherein R¹ -R⁶ are each hydrogen or a hydrocarbyl group, provided thatat least one of R¹ -R⁶ is a hydrocarbyl group and further provided thatthe structure of the residual double bond in the polymerized block I hasthe following formula ##STR2## wherein R^(I), R^(II), R^(III) and R^(IV)are each hydrogen or a hydrocarbyl group, provided that either bothR^(I) and R^(II) are hydrocarbyl groups or both R^(III) and R^(IV) arehydrocarbyl groups; B is a block of a polymer of at least one conjugateddiene, different from that used to polymerize the I block, having atleast four (4) carbon atoms and the following formula ##STR3## whereinR⁷ -R¹² are each hydrogen or a hydrocarbyl group, provided that thestructure of the residual double bond in the polymerized conjugateddiene of formula (3) (block B) has the following formula ##STR4##wherein R^(a), R^(b), R^(c) and R^(d) are each hydrogen (H) or ahydrocarbyl group, provided that one of R^(a) or R^(b) is hydrogen, oneof R^(c) or R^(d) is hydrogen and at least one of R^(a), R^(b), R^(c) orR^(d) is a hydrocarbyl group; x is at least 1, preferably 1 to 30, morepreferably 2 to 20, and most preferably 3 to 10, and y is at least 25,preferably 30 to 275, more preferably 85 to 225, and most preferably 130to 200. It will be apparent to those skilled in the art that in theresidual double bond of formula (2), R^(I), R^(II), R^(III) and R^(IV)may all be hydrocarbyl groups.

The hydrocarbyl group or groups in the formulae (1) and (2) are the sameor different and they are substituted or unsubstituted alkyl, alkenyl,cycloalkyl, cycloalkenyl, aryl, alkaryl or aralkyl groups or any isomersthereof. Examples of suitable conjugated dienes used to polymerize the Iblock are isoprene, 2,3-dimethyl butadiene, 2-methyl-1,4-pentadiene ormyrcene. The hydrocarbyl groups in formulae (3) and (4) are the same asthose described above in conjunction with the discussion of formulae (1)and 2. Suitable conjugated dienes used to polymerize the B block are1,3-butadiene or 1,3-pentadiene. After the polymerization is completed,the block polymer is hydrogenated so that the block B is selectivelyhydrogenated to such an extent that it contains substantially none ofthe original unsaturation, while each of the blocks I retains asufficient amount of its original unsaturation to cure (or vulcanize)the block copolymer. The block copolymer is terminated at both ends witha block I.

In an alternative embodiment, there is provided a block copolymercomprising at least three alternating blocks:

    (A).sub.x -(D).sub.y -(A).sub.x

wherein the block A is a block or random copolymer of about 30 to about70%, preferably about 40 to about 60%, by mole of at least onearyl-substituted olefin, such as styrene, 2-phenyl alpha-olefins,alkylated styrene, vinyl naphthalene or alkylated vinyl naphthalene, andabout 30 to about 70%, preferably about 40 to about 60%, by mole of atleast one conjugated diene of formula (1), discussed above; D is a blockof a polymer of at least one conjugated diene of formula (3), discussedabove, which is different from the conjugated diene of formula (1) usedto polymerize the block (A); x is about 2 to about 30%, preferably about4 to about 16%, by wt., of the weight of the triblock copolymer, and yis about 40 to about 96%, preferably about 68 to about 92%, by wt., ofthe weight of the triblock copolymer. Examples of suitable conjugateddienes used to polymerize the A block are isoprene, 2,3-dimethylbutadiene, myrcene or 2-methyl-1,3-pentadiene. Suitable conjugateddienes used to polymerize the D block are 1,3-butadiene or1,3-pentadiene.

After this block copolymer is polymerized, it is hydrogenated, so thatthe block D is selectively hydrogenated to such an extent that itcontains substantially none of the original unsaturation, while each ofthe blocks A retains a sufficient amount of the original unsaturation ofthe conjugated diene present in each of the A blocks to cure the blockcopolymer. The block copolymer of this embodiment is terminated at bothends with a block A.

The blocks A and I are referred to hereinafter as the "terminal blocks",and the blocks B and D as the "middle blocks".

Yet another embodiment is directed to a block copolymer comprising atleast three alternating blocks:

    I-D-A

wherein the blocks I, D and A are polymerized from the same monomers asdiscussed above for the respective blocks. The block copolymer comprisesabout 1 to about 15, preferably about 2 to about 8% wt. of the block I,about 2 to about 30, preferably about 4 to about 16% wt. of the blocks Aand about 55 to about 97, preferably about 76 to about 94% wt. of theblocks D. The block A of this copolymer is either a block or a randomcopolymer of about 30 to about 70% by mole of at least onearyl-substituted olefin and about 30 to about 70% by mole of at leastone conjugated diene of formula (1).

Another embodiment of the invention is directed to random copolymers ofat least one conjugated diene of formula (1) and at least one conjugateddiene of formula (3), both discussed above, provided that the diene offormula (3) is different from the diene of formula (1). This randomcopolymer contains about 1.0 to about 25, preferably about 1.0 to about10% by mole of the polymerized conjugated diene of formula (1) and about75 to about 99%, preferably about 90 to about 99% by mole of theconjugated diene of formula (3). This random copolymer is alsoselectively hydrogenated, so that the polymerized diene of formula (3)contains none of the original unsaturation, while the polymerized dieneof formula (1) retains a sufficient amount of the original unsaturationto cure the random copolymer.

Another embodiment of this invention is directed to random copolymers ofat least one aryl-substituted olefin, at least one conjugated diene offormula (1) and at least one conjugated diene of formula (3), bothdiscussed above, provided that the conjugated diene of formula (1) isdifferent from the conjugated diene of formula (3). This randomcopolymer contains about 0.3 to about 15% by mole of thearyl-substituted olefin, about 1.0 to about 25%, preferably about 1.0 toabout 10%, by mole of the conjugated diene of formula (1), and theremainder of the conjugated diene of formula (3). This random copolymeris also hydrogenated, so that the polymerized diene of formula (3) isselectively hydrogenated to such an extent that it contains none of theoriginal unsaturation, while the polymerized diene of formula (1)retains a sufficient amount of the original unsaturation to cure therandom copolymer.

Yet another embodiment of the invention is directed to star-branchedblock and random polymers. The star-branched block polymers are madefrom any combination of blocks I and B, A and D, or I, D and A,providing that each free end (i.e., uncoupled end) of the star-branchedpolymer is either an I or an A block, respectively. The star-branchedblock polymers are selectively hydrogenated to such an extent thatblocks B or D contain substantially none of the original unsaturation,while each of the blocks I or A, respectively, retains a sufficientamount of the original unsaturation of the conjugated dienes presenttherein to cure the star-branched block polymers.

The star-branched random polymers are made from any combination ofdienes of formulae (1) and (3), providing that the diene of formula (1)is different from the diene of formula (3), or from at least onearyl-substituted olefin, at least one diene of formula (1) and at leastone diene of formula (3), providing that the diene of formula (3) isdifferent from the diene of formula (1). The star-branched randompolymers are selectively hydrogenated, so that the polymerized diene offormula (3) contains none of the original unsaturation, while thepolymerized diene of formula (1) retains a sufficient amount of theoriginal unsaturation to cure the star-branched random polymers.

The copolymers of all embodiments are prepared under anionicpolymerization conditions. After the selective hydrogenation reaction,the hydrogenation catalyst is removed from the polymer.

In all embodiments of this invention, whenever a reference is made tothe "residual double bond" of the block or random polymer (orcopolymer), it is understood to be the residual double bond prior to thehydrogenation reaction. The structure of the residual double bond can bedetermined in any conventional manner, as is known to those skilled inthe art, e.g., by infrared (IR) or NMR analysis.

The term "original unsaturation", as used herein, means the sum total ofthe unsaturated groups present in all blocks of the copolymer prior tothe selective hydrogenation reaction. The unsaturation can be quantifiedin any conventional manner, e.g., by reference to the Iodine Number ofthe polymer. For example, for a block copolymer of the first embodimentwherein the I blocks are polyisoprene and the B block is polybutadiene,the Iodine Number before selective hydrogenation for each of the Iblocks is 373 and for the B block it is 470. After selectivehydrogenation is completed, the Iodine Number for each of the I blocksis about 75 to about 373, and for the B block it is about 0 to about 50,preferably about 0 to about 2.5 and most preferably about 0 to about 1.

In any polymers of any of the embodiments of this invention, themicrostructure of the polymerized conjugated diene of formula (3), e.g.,blocks B or D in the block copolymers, must be such that the polymer isnot excessively crystalline after the selective hydrogenation reaction,i.e., after the selective hydrogenation reaction the polymer must retainits elastomeric properties e.g., the polymer should contain not morethan about 10% of polyethylene crystallinity. This is accomplished byintroducing side branches into the polymerized conjugated diene offormula (3), e.g., by controlling the microstructure of 1,3-butadiene ifit is the predominant monomer in the diene of formula (3), by using amixture of dienes of formula (3) containing less than predominantamounts of 1,3-butadiene or by using a single diene of formula (3),other than 1,3-butadiene. More particularly, if the conjugated diene(s)of formula (3) is predominantly (at least 50% by mole) 1,3-butadiene,the side branches are introduced into the polymer by insuring that thepolymerized diene of formula (3) contains a sufficient amount of the1,2-units to prevent the selectively hydrogenated polymer from beingexcessively crystalline. Thus, if the conjugated diene of formula (3) ispredominantly (at least 50% by mole, e.g., 100% by mole) 1,3-butadiene,the polymerized diene of formula (3), prior to the selectivehydrogenation reaction, must contain not more than about 75% wt.,preferably about 10 to about 70% wt., and most preferably about 35 toabout 55% wt. of the 1,4-units, and at least about 25% wt., preferablyabout 30 to about 90% wt., and most preferably about 45 to about 65% wt.of the 1,2-units. If the polymerized diene(s) of formula (3) containsless than 50% by mole of 1,3-butadiene, e.g., 1,3-pentadiene is used asthe only diene of formula (3), the microstructure of the polymerizeddiene of formula (3) prior to the selective hydrogenation reaction isnot critical since, after hydrogenation, the resulting polymer willcontain substantially no crystallinity.

In all embodiments of the invention, mixtures of dienes of formulae (1)or (3) may be used to prepare block copolymers (I)_(x) -(B)_(y)-(I)_(x), (A)_(x) -(D)_(y) -(A)_(x) or I-D-A, any of the randomcopolymers or star-branched block and random polymers of the invention.Similarly, mixtures of aryl-substituted olefins may also be used toprepare block, random or star-branched copolymers of this invention.Accordingly, whenever a reference is made herein to a diene of formulae(1) or (3), or to an aryl-substituted olefin, it may encompass more thanone diene of formulae (1) or (3), respectively, and more than onearyl-substituted olefin.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the relationship of viscosity as a function of molecularweight for the unhydrogenated isoprene-butadiene-isoprene triblockpolymer of this invention.

FIG. 2 shows the relationship of viscosity as a function of molecularweight for the hydrogenated isoprene-butadiene-isoprene triblock polymerof this invention.

FIGS. 3 and 4 show properties of the cured selectively hydrogenatedisoprene-butadiene-isoprene polymers of this invention as a function ofmolecular weight thereof.

DETAILED DESCRIPTION OF THE INVENTION

The block copolymers of this invention comprise three or morealternating blocks, identified above. Linear block copolymers havingmore than three blocks are contemplated herein, although they do notappear to exhibit better properties than the block copolymers containingonly three blocks. However, star-branched block polymers containing anycombination and number of blocks I and B, A and D, or I, D and A arealso contemplated herein, providing that they are terminated either byblocks I or A, respectively. The central (middle) block of each linearthree block unit is substantially completely saturated, while theterminal blocks contain controlled levels of unsaturation providing ahydrocarbon elastomer with α-ω unsaturation. The length of the centralsaturated block defines the distance between crosslinks (M_(c)) in thevulcanized elastomers. Because of the α-ω placement of the unsaturation,very low levels of residual double bonds are required to attainexcellent vulcanization. The low level of unsaturation in theselectively hydrogenated triblock polymer and its terminal positioningprovide excellent oxidative stability to the polymers of this invention.

Without wishing to be bound by any theory, it is believed that the α-ωplacement of unsaturation in the polymers of this invention imparts tothe polymers excellent elastomeric properties which were absent in priorart thermosetting liquid elastomers which required a multiplicity ofrelatively closely spaced crosslinks.

The combination of elastomeric properties and oxidative stabilitypossessed by the polymers of this invention makes them suitable for manyend uses, such as sealants, caulks and adhesives.

Many variations in composition, molecular weight, molecular weightdistribution, relative block lengths, microstructure, branching and Tg(glass transition temperature) attainable with the use of anionictechniques employed in the preparation of our polymers will be obviousto those skilled in the art.

While not wishing to limit the molecular weight range of liquidelastomers prepared according to our invention, the minimum molecularweight for these liquid polymers is at least about 2,000, preferablyabout 5,000 to about 15,000, and most preferably about 7,500 to about10,000. Star-branched block and random polymers of this invention mayhave substantially higher molecular weights and still retain liquidproperties. For example, liquid star-branched block polymers havingmolecular weight of about 34,000 have been prepared. The blockcopolymers of this invention are vulcanizable. Without wishing to bebound by any theory of operability, it is believed that they can becrosslinked (or vulcanized) in a controlled manner through theunsaturated groups on the terminal blocks to provide a very strong andorderly matrix of crosslinkages having almost uniform distribution ofmolecular weights between crosslinks, M_(c). The random andstar-branched copolymers of this invention are also vulcanizable. Thedesignation M_(c), as used herein for the block copolymers means thelength of the middle block. For random copolymers, M_(c) is calculatedby dividing number average molecular weight, M_(n), of the polymer bythe average number of crosslinks per chain plus 1.

The invention will be described hereinafter in terms of the embodimentsthereof summarized above. However, it will be apparent to those skilledin the art, that the invention is not limited to these particularembodiments, but, rather, it covers all the embodiments encompassed bythe broadest scope of the description of the invention.

Liquid Block Copolymers From at Least Two Dissimilar Conjugated Dienes

In this embodiment of the invention, there is polymerized a blockcopolymer comprising at least three alternating blocks:

    (I).sub.x -(B).sub.y -(I).sub.x

wherein:

I is a block of at least one polymerized conjugated diene having atleast five (5) carbon atoms and the following formula ##STR5## whereinR¹ -R⁶ are each hydrogen or a hydrocarbyl group, provided that at leastone of R¹ -R⁶ is a hydrocarbyl group, and further provided that thestructure of the residual double bond in the polymerized block I has thefollowing formula ##STR6## wherein R^(I), R^(II), R^(III) and R^(IV) areeach hydrogen or a hydrocarbyl group, provided that either both R^(I)and R^(II) are hydrocarbyl groups or both R^(III) and R^(IV) arehydrocarbyl groups;

B is a block of at least one polymerized conjugated diene, differentfrom that used to polymerize block I, having at least four (4) carbonatoms and the following formula ##STR7## wherein R⁷ -R¹² are eachhydrogen or a hydrocarbyl group, provided that the structure of theresidual double bond in the polymerized block B has the followingformula ##STR8## wherein R^(a), R^(b), R^(c) and R^(d) are each hydrogen(H) or a hydrocarbyl group, provided that one of R^(a) or R^(b) ishydrogen, one of R^(c) or R^(d) is hydrogen and at least one of R^(a),R^(b), R^(c) or R^(d) is a hydrocarbyl group;

x is at least 1, preferably 1 to 15, more preferably 2 to 10, and mostpreferably 2 to 7, y is at least 25, preferably 90 to 300, morepreferably 130 to 200, and most preferably 140 to 200. The abovedefinition of x means that each of the I blocks is polymerized from atleast 1, preferably from 1-15, more preferably from 2-10 and mostpreferably from 2-7 monomer units. For some special applications, eachof the I blocks is polymerized from 20-30 monomer units. The blockpolymers containing such large I blocks have increased vulcanizationrate, as compared to those containing smaller I blocks, and areco-vulcanizable with diene rubbers available in the art, e.g.,polybutadiene and natural rubbers. The block polymers containing suchlarge I blocks can be blended with diene rubbers by conventional methodsand subsequently vulcanized to produce novel compositions of thisinvention. The resulting materials are expected to have increasedoxidation and ozone degradation resistance as compared to known dienerubbers alone, and therefore are expected to be valuable materials forthe production of white sidewalls of tires and similar articles.

Similarly, the above definition of y means that each of the B blocks ispolymerized from at least 25, preferably from 90 to 300, more preferablyfrom 130 to 200, and most preferably from 140 to 200 monomer units. Inthe residual double bond of formula (2), R^(I), R^(II), R^(III) andR^(IV) may all be hydrocarbyl groups.

The structures of the residual double bonds defined by formulae (2) and(4) are necessary to produce copolymers which can be selectivelyhydrogenated in the manner described herein, to produce the selectivelyhydrogenated block and random copolymers of this invention.

The block copolymer comprises about 0.5 to about 25%, preferably about 1to about 5% by wt. of the I blocks, and about 75 to about 99.5%,preferably about 95 to about 99% by wt. of the B blocks.

The hydrocarbyl group or groups in the formulae (1) and (2) are the sameor different and they are substituted or unsubstituted alkyl, alkenyl,cycloalkyl, cycloalkenyl, aryl, alkaryl or aralkyl groups or any isomersthereof. Suitable hydrocarbyl groups are alkyls of 1-20 carbon atoms,alkenyls of 1-20 carbon atoms, cycloalkyls of 5-20 carbon atoms,cycloalkenyls of 5-20 carbon atoms, aryls of 6-12 carbon atoms, alkarylsof 7-20 carbon atoms or aralkyls of 7-20 carbon atoms. Examples ofsuitable alkyl groups are methyl, ethyl, propyl, butyl, pentyl, hexyl,heptyl, octyl, decyl, methyl-decyl or dimethyl-decyl. Examples ofsuitable alkenyl groups are ethenyl, propenyl, butenyl, pentenyl orhexenyl. Examples of suitable cycloalkyl groups are cyclohexyl ormethylcyclohexyl. Examples of suitable cycloalkenyl groups are 1-, 2-,or 3-cyclohexenyl or 4-methyl-2-cyclohexenyl. Examples of suitable arylgroups are phenyl or diphenyl. Examples of suitable alkaryl groups are4-methyl-phenyl (p-tolyl) or p-ethyl-phenyl. Examples of suitablearalkyl groups are benzyl or phenethyl. Suitable conjugated dienes offormula (1) used to polymerize the I block are isoprene,2,3-dimethyl-butadiene, 2-methyl-1,3-pentadiene, myrcene,3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene,2-phenyl-1,3-butadiene, 2-phenyl-1,3-pentadiene,3-phenyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene,2-hexyl-1,3-butadiene, 3-methyl-1,3-hexadiene, 2-benzyl-1,3-butadiene,2-p-tolyl-1,3-butadiene or mixtures thereof, preferably isoprene,myrcene or 2-methyl-1,3-pentadiene, and most preferably isoprene.

The hydrocarbyl group or groups in the formula (3) may or may not be thesame as those in formula (4). These hydrocarbyl groups are the same asthose described above in conjunction with the discussion of thehydrocarbyl groups of formulae (1) and (2). Suitable monomers for the Bblock are 1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, 1,3-hexadiene,1,3-heptadiene, 2,4-heptadiene, 1,3-octadiene, 2,4-octadiene,3,5-octadiene, 1,3-nonadiene, 2,4-nonadiene, 3,5-nonadiene,1,3-decadiene, 2,4-decadiene, 3,5-decadiene or mixtures thereof,preferably 1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene or1,3-hexadiene, and most preferably it is 1,3-butadiene. It is preferredthat each of the B blocks is polymerized from a single monomer.

The block copolymer of this embodiment is terminated at both ends with ablock I.

The scope of this embodiment, and of any other embodiments of theinvention wherein the block B is used, also encompasses polymers whereinthe central block B may comprise copolymers of one or more conjugateddiene of formula (3) and controlled amounts (about 0.3 to about 30 mole%) of an aryl-substituted olefin, e.g., styrene or other suitablemonomers (such as alkylated styrene, vinyl napthalene or alkylated vinylnaphthalene) incorporated for control of glass transition temperature(Tg), density, solubility parameters and refractive index. Suitablearyl-substituted olefins are those described below in conjunction withthe second embodiment of the invention. Similarly, the scope of thisembodiment also encompasses polymers wherein the central block B may becomprised of copolymers of one or more conjugated diene of formula (3)and any other anionically polymerizable monomer capable of polymerizingwith the conjugated diene of formula (3).

It will be apparent to those skilled in the art that proper choice ofpolymerization parameters can produce polymers with a great variety ofcompositional and structural differences, falling within the scope ofour invention. Changes in composition of the central block B control thenature of the rubbery properties while changes in the terminal blockspermit response to different vulcanizing agents, e.g., quinone dioxime,sulfur-based and phenolic resin cure systems.

The block copolymer is polymerized by any conventional blockcopolymerization process, such as anionic polymerization, discussed indetail below. As will be apparent to those skilled in the art, thecopolymer of this embodiment contains at least three alternating blocks,I-B-I, referred to herein as the triblocks or triblock units, but it maycontain an unlimited number of blocks, so long as the entire blockcopolymer is terminated at both ends by the I blocks. Polymers havingmore than three blocks (such as five) allow crosslinking to take placeat the ends and in the central portion, but maintain a controlled largedistance between crosslinks. It is important to have the block copolymerterminated at each end with the I blocks to assure that there areunsaturated groups at each end of the block copolymer enabling the blockcopolymer to be cross-linked or functionalized at the terminal endsthereof. The term "functionalized" is used herein to describe chemicalmodifications of the unsaturated groups to produce functional groups,the nature of which is described in detail below. The crosslinking ofthe functionalized and nonfunctionalized copolymer chains is conductedin a conventional manner and is described below.

After the block copolymer is polymerized, it is subjected to a selectivehydrogenation reaction during which the B blocks of the block copolymerare selectively hydrogenated to such an extent that they containsubstantially none of the original unsaturation, while the I blocksretain a sufficient amount of their original unsaturation to cure theblock copolymer. Generally, for a block copolymer wherein the I and Bblocks are polymerized from any of the monomers discussed above, theIodine Number for the I blocks after the selective hydrogenationreaction is about 20 to about 100%, preferably about 50 to about 100%,and most preferably about 100% of the Iodine Number prior to theselective hydrogenation reaction and for the B blocks it is about 0 toabout 10%, preferably about 0 to about 0.5%, and most preferably about 0to about 0.2% of the Iodine Number prior to the selective hydrogenationreaction. The Iodine Number, as is known to those skilled in the art, isdefined as the theoretical number of grams of iodine which will add tothe unsaturation in 100 grams of olefin and is a quantitative measure ofunsaturation.

In this embodiment of the invention, although the microstructure of theI blocks is not critical and may consist of 1,2-, 3,4- and/or 1,4-units,schematically represented below for the polyisoprene blocks, when apolar compound is used during the polymerization of the I block, the Iblocks comprise primarily (at least about 80% wt.) 3,4-units, the restbeing primarily (about 20% wt.) 1,2-units; when the polar compound isnot used during the polymerizaton of the I block, the I blocks compriseprimarily (about 80% wt.) 1,4-units, the rest being primarily 1,2- and3,4-units. ##STR9##

The microstructure of the B blocks, when the predominant monomer used topolymerize the B blocks is 1,3-butadiene, should be a mixture of 1,4-and 1,2-units schematically shown below for the polybutadiene blocks:##STR10## since the hydrogenation of the predominantly1,4-microstructures produces a crystalline polyethylene segment. Themicrostructure of the I and B blocks (as well as of the polymerizedconjugated dienes of formulae (1) or (3) in any polymers of thisinvention) is controlled in a conventional manner, e.g., by controllingthe amount and nature of the polar compounds used during thepolymerization reaction, and the reaction temperature. In oneparticularly preferred embodiment, the B block contains about 50% of the1, 2- and about 50% of the 1,4-microstructure. If the B block ispoly-1,3-butadiene, the hydrogenation of the B segment containing about50 to about 60% of the 1,2-microstructure content produces anelastomeric center block which is substantially an ethylene-butene-1copolymer having substantially no crystallinity. If the B block ispolymerized from 1,3-pentadiene, it is preferred that it havepredominantly (at least 50%) of 1,4-microstructure which, afterhydrogenation, produces a substantially non-crystalline elastomericblock.

The terms 1,2-, 1,4-, and 3,4-microstructure or units as used in thisapplication refer to the products of polymerization obtained by the1,2-, 1,4- and 3,4-, respectively, additions of two monomer units.

We surprisingly discovered that the polymerized conjugated dienes offormula (3), e.g., the B blocks, of the polymers of this invention areselectively hydrogenated in our hydrogenation process much faster thanthe polymerized conjugated dienes of formula (1), e.g., the I blocks.This is not evident from the teachings of Falk, discussed above, becauseFalk teaches that double bonds of the disubstituted 1,4-polybutadieneunits are hydrogenated selectively in the presence of double bonds ofthe trisubstituted 1,4-polyisoprene units (which are not hydrogenated).We surprisingly discovered that the disubstituted double bonds of the1,4-polybutadiene units are hydrogenated along with the monosubstituteddouble bonds of the 1,2-polybutadiene units, while the disubstituteddouble bonds of the 3,4-polyisoprene units are hydrogenated at a muchslower rate than the aforementioned polybutadienes. Thus, in view ofFalk's disclosure it is surprising that the disubstituted double bondsof the 1,4-polybutadiene units are hydrogenated selectively in thepresence of the disubstituted double bonds of the 3,4-polyisopreneunits. This is also surprising in view of the teachings of Hoxmeier,Published European Patent Application, Publication No. 0 315 280 , whodiscloses that the disubstituted double bonds of the 1,4-polybutadieneunits, monosubstituted double bonds of the 1,2-polybutadiene units anddisubstituted double bonds of the 3,4-polyisoprene units arehydrogenated simultaneously at substantially the same rates. Forexample, for the block copolymers of this invention, wherein the I blockis polyisoprene and the B block is polybutadiene, Fourier TransformInfrared (FTIR) analysis of selectively hydrogenated triblock polymersindicates that the hydrogenation of the double bonds of the1,2-polybutadiene units proceeds most rapidly, followed by thehydrogenation of the double bonds of the 1,4-polybutadiene units.Infrared absorptions caused by these groups disappear prior toappreciable hydrogenation of the polyisoprene units.

After the I-B-I block copolymer is prepared, it is subjected to aselective hydrogenation reaction to hydrogenate primarily the B block ofeach of the triblocks. The selective hydrogenation reaction and thecatalyst are described in detail below. After the hydrogenation reactionis completed, the selective hydrogenation catalyst is removed from theblock copolymer, and the polymer is isolated by conventional procedures,e.g., alcohol flocculation, steam stripping of solvent or non-aqueoussolvent evaporation. An antioxidant, e.g., Irganox 1076 (fromCiba-Geigy), is normally added to the polymer solution prior to polymerisolation.

The isolated polymer is vulcanizable through the α-ω unsaturated endblocks I by a number of well known processes utilized currently forthermosetting hydrocarbon elastomers. Such processes are detailed inRUBBER TECHNOLOGY, THIRD EDITION, VAN NOSTRAND REINHOLD COMPANY, NewYork, 1987, Maurice Morton, Editor, Chapters 2, 9 and 10, incorporatedherein by reference.

Triblock Copolymer Of Poly-Diene Center Block And Terminal Blocks ofAryl-Substituted Olefin/Diene Copolymer

In this alternative embodiment of the invention, the block copolymercomprises at least one triblock of:

    (A).sub.x -(D).sub.y -(A).sub.x

wherein the block A is a copolymer of about 30 to about 70%, preferablyabout 40 to about 60% by mole of at least one aryl-substituted olefin,and about 30 to about 70%, preferably about 40 to about 60%, by mole ofat least one conjugated diene of formula (1), defined above. The block Ais either a block or a random copolymer. The most preferred conjugateddiene of formula (1) is isoprene. In this block copolymer, D is a blockof a polymer of at least one conjugated diene of formula (3), discussedabove, which is different from the conjugated diene of formula (1) usedto polymerize the block A. In this block copolymer, x represents thetotal number of monomer units in the block A, such that the blockcopolymer comprises about 2 to about 30%, preferably about 4 to about16% by wt. of the A blocks and y represents the total number of monomerunits in the block D, such that the block copolymer comprises about 40to about 96%, preferably about 68 to about 92% by wt. of the D blocks.The block copolymer of this embodiment may contain several blocks of theaforementioned formula, e.g., 5, so long as it is terminated at bothends with the block A, but, preferably, it contains only three blocksA-D-A. Suitable aryl-substituted olefins used to polymerize the block Ahave the formula ##STR11##

where Ar is phenyl, alkyl-substituted phenyl, naphthyl oralkyl-substituted naphthyl, and R^(e) is hydrogen, methyl, ethyl,propyl, butyl or aryl. Examples of suitable aryl-substituted olefins arestyrene, 2-phenyl alpha-olefins, such as alpha-methyl styrene,1,1-diphenyl ethylene, alkylated styrenes, vinyl naphthalene, or anyalkylated vinyl naphthalenes. Suitable alkyl substituents in thealkylated styrenes or alkylated vinyl naphthalenes are methyl, ethyl,propyl, sec-butyl and tert-butyl. Each of the alkylated styrenes orvinyl naphthalenes may contain one or more alkyl substituents. Preferredaryl-substituted olefins are styrene, vinylnaphthalene, alpha-methylstyrene, vinyltoluene and diphenylethylene. The microstructure of thepolymerized diene of formula (1) is not critical, but can be controlledin the manner discussed above. The block copolymer of this embodiment ispolymerized by any conventional block copolymerization process, such asanionic polymerization discussed in detail below.

The scope of this embodiment, and of any other embodiment of theinvention wherein the block D is used, also encompasses polymers whereinthe central (middle) block D may be comprised of copolymers of one ormore conjugated diene of formula (3) and controlled amounts (about 0.3to about 30 mole %) of an aryl-substituted olefin, e.g., styrene orother suitable monomers (such as alkylated styrene, vinyl napthalene oralkylated vinyl napthalene), incorporated for control of glasstransition temperature (Tg), density, solubility parameters andrefractive index.

The scope of this embodiment, and of any other embodiment of theinvention using the block A, also encompasses polymers wherein theblocks A are prepared by, initially, polymerizing at least onearyl-substituted olefin alone, and subsequently reacting the resultingpoly-aryl-substituted olefin with any compounds which, after chemicalreaction with the poly-aryl-substituted olefin, will provide theresidual double bonds on the A blocks, as defined above in conjunctionwith the discussion of the conjugated diene of formula (1). Theresulting block A will therefore have substantially the same residualunsaturation (residual double bonds) on the terminal blocks A as anyother block A made in accordance with this embodiment (or any otherembodiment using the block A).

In the most preferred embodiment, the block A of this triblock copolymeris polymerized from isoprene and styrene in the molar proportion ofabout 1:1. Most preferably, in this embodiment of the invention, the Ablock is polymerized from isoprene and styrene, and the D block from1,3-butadiene, in such proportions that the final copolymer comprisesabout 1.5 to about 6% wt. of the isoprene, about 2.5 to about 10% wt. ofthe styrene, and about 84 to about 96% wt. of the butadiene units.

After the polymerization is completed, the block copolymer is subjectedto a selective hydrogenation reaction. After selective hydrogenation,the polymer contains a sufficient amount of its original unsaturation inthe terminal blocks A to cure the block polymer, thereby permittingchemical crosslinking or functionalization in the manner discussedbelow, while the middle block D contains substantially none of theoriginal unsaturation. For example, for a block copolymer wherein the Ablocks are copolymers of styrene and isoprene and the D block ispolybutadiene, the Iodine Number before selective hydrogenation for eachof the A blocks is 120-180 and for the D block it is 470. Afterselective hydrogenation, the Iodine Number for each of the A blocks isabout 20 to about 180 and for the D block it is about 0 to about 10, andpreferably about 0 to about 2.5. Generally, for a block copolymerwherein the A and D blocks are polymerized from any of the monomerssuitable for their polymerization, discussed above, the Iodine Numberfor the A blocks after the selective hydrogenation is completed is about20 to about 100%, preferably about 100% of the Iodine Number prior tothe selective hydrogenation reaction, and for the D blocks it is about 0to about 10%, preferably about 0 to about 0.5%, and most preferablyabout 0% of the Iodine Number prior to the selective hydrogenationreaction. Thus, in this embodiment, the block D is also selectivelyhydrogenated in the same manner as discussed above for the central blockB of the first embodiment of the invention.

The block copolymer of this embodiment is also a liquid, and, afterselective hydrogenation, the unsaturated groups in the terminal A blocksof each of the triblocks provide a means of crosslinking the copolymeror functionalizing the terminal blocks A, in the manner discussedelsewhere in this application.

Triblock Copolymer of at Least One Poly-Diene Center Block, and at LeastOne Terminal Block of Aryl-Substituted Olefin/Diene Copolymer

In this embodiment of the invention, the block copolymer comprises atleast one triblock of:

    I-D-A

where the block I is a polymer of at least one polymerized diene offormula (1), defined above, the block D is a polymer of at least oneconjugated diene of formula (3), defined above, which is different fromthe conjugated diene of formula (1), and the block A is a copolymer ofat least one aryl-substituted olefin and at least one conjugated dieneof formula (1), both defined above. The block A is a copolymer of about30 to about 70%, preferably about 40 to about 60% by mole of at leastone aryl-substituted olefin, and about 30 to about 70%, preferably about40 to about 60% by mole of at least one conjugated diene of formula (1),preferably isoprene. This block copolymer comprises about 1 to about 15,preferably about 2 to about 8% wt. of the blocks I, about 2 to about 30,preferably about 4 to about 16% wt. of the blocks A, and about 55 toabout 97, preferably about 76 to about 94% wt. of the blocks D. Theblock of this embodiment may also contain several, e.g. 5-7, blocks ofthe aforementioned formulae so long as it is terminated at both endsthereof with blocks I or A. The block copolymer is polymerized by anyconventional block copolymerization process, such as anionicpolymerization, discussed in detail below.

The scope of this embodiment of the invention also encompasses polymerswherein the central block D may be comprised of copolymers of one ormore conjugated diene of formula (3) and controlled amounts (about 0.3to about 30 mole %) of an aryl-substituted olefin, e.g., styrene orother suitable monomers (such as alkylated styrene, vinyl napthalene oralkylated vinyl napthalene), incorporated for control of glasstransition temperature (T_(g)), density, solubility parameters andrefractive index. Suitable aryl-substituted olefins are those describedbelow in conjunction with the second embodiment of the invention.Similarly, the scope of this embodiment also encompasses polymerswherein the central block D may be comprised of copolymers of one ormore conjugated diene of formula (3) and any other anionicallypolymerizable monomer capable of polymerizing with the conjugated dieneof formula (3).

This embodiment also encompasses polymers wherein the blocks A areprepared by, initially, polymerizing at least one aryl-substitutedolefin alone, and, subsequently, reacting the resultingpoly-aryl-substituted olefin with any compounds which, after chemicalreaction with the poly-aryl-substituted olefin, will provide theresidual double bonds to the A blocks, as defined above in conjunctionwith the discussion of the conjugated diene of formula (1). Theresulting block A will therefore have substantially the same residualunsaturation (residual double bonds) on the terminal blocks A as anyother block A made in accordance with this embodiment.

After the polymerization is completed the block copolymer is subjectedto a selective hydrogenation reaction. After selective hydrogenation,the polymer contains a sufficient amount of its original unsaturation inthe terminal blocks I and A to cure the block copolymer, therebypermitting chemical crosslinking or functionalization in the mannerdiscussed below, while the middle block D contains substantially none ofthe original unsaturation. Generally, for a block copolymer wherein theI, D and A blocks are polymerized from any of the monomers suitable fortheir polymerization, discussed above, the Iodine Number for the I and Ablocks after the selective hydrogenation is completed is about 10 toabout 100%, preferably abour 100% of the Iodine Number prior to theselective hydrogenation reaction, and for the D blocks it is about 0 toabout 10%, preferably about 0 to about 0.5%, and most preferably 0% ofthe Iodine Number prior to the selective hydrogenation reaction. Thus,in this embodiment, the block D is also selectively hydrogenated in thesame manner as discussed above, while the terminal blocks I and A retaina substantial amount of their original unsaturation.

The block copolymer of this embodiment is also a liquid, and, afterselective hydrogenation, the unsaturated groups in the terminal blocks Iand A of each of the triblocks provide a means of crosslinking thecopolymer or functionalizing the terminal blocks I and A, in the mannerdiscussed elswhere in this application.

Random Copolymers

Random copolymers of this invention have controlled amounts ofunsaturation incorporated randomly in an otherwise saturated backbone.In contrast to EPDM, the level of unsaturation can be inexpensively andeasily controlled, e.g., to produce polymers having Iodine Number ofabout 5 to about 100, to provide a wide variation in vulcanization rateand potential co-curability with various highly unsaturated rubbersbased on butadiene or isoprene.

In one embodiment, the random copolymers are polymerized from the samemonomers used to polymerize the block copolymers (I)_(x) -(B)_(y)-(I)_(x), i.e., from at least one conjugated diene of formula (1) and atleast one conjugated diene of formula (3), both defined above, providedthat the diene of formula (1) is different from the diene of formula(3). This random copolymer contains about 1.0 to about 25%, preferablyabout 1.0 to about 10% by mole of the polymerized conjugated diene offormula (1) and about 75 to about 99%, preferably about 90 to about 99%by mole of the polymerized conjugated diene of formula (3). Suitableconjugated dienes of formula (1) are exemplified above. The mostpreferred conjugated diene of formula (1) for the copolymerization ofthese random copolymers is isoprene. Suitable conjugated dienes offormula (3) are also exemplified above. 1,3-butadiene is the mostpreferred conjugated diene of formula (3) for the polymerization of therandom copolymer of this embodiment. Thus, most preferably, in thisembodiment, the random copolymer is polymerized from isoprene and1,3-butadiene, and it contains about 1 to about 20% wt. of the isopreneunits and about 80 to about 99% wt. of the butadiene units. The isopreneunits have primarily (i.e., about 50 to about 90% wt.) the3,4-microstructure.

In another embodiment, the random copolymers are polymerized from thesame monomers used to polymerize the block copolymers (A)_(x) -(C)_(y)-(A)_(x), i.e., from at least one aryl-substituted olefin, at least oneconjugated diene of formula (1), and at least one conjugated diene offormula (3), providing that the conjugated diene of formula (1) isdifferent from the conjugated diene of formula (3) used in thepolymerization. The conjugated dienes of formulae (1) and (3) aredefined above and the aryl-substituted olefins are also the same asthose defined above. This alternative random copolymer contains about0.3 to about 15% by mole of the aryl-substituted olefin, about 1.0 toabout 25%, preferably about 1.0 to about 10%, by mole of the conjugateddiene of formula (1), the remainder being the conjugated diene offormula (3).

The random copolymers are subjected to the selective hydrogenationreaction discussed above for the block copolymers, during whichpolymerized conjugated diene units of formula (3) are substantiallycompletely hydrogenated, while the polymerized conjugated diene units offormula (1) are hydrogenated to a substantially lesser extent, i.e., tosuch an extent that they retain a sufficient amount of their originalunsaturation to vulcanize the copolymer, thereby producing liquidelastomers having random unsaturation proportional to the unsaturationin the polymerized dienes of formula (1). For example, for a randomcopolymer polymerized from a diene of formula (1) and a different dieneof formula (3), the Iodine Number before selective hydrogenation for thepolymer is about 450. After selective hydrogenation, the Iodine Numberfor the polymer is about 10 to about 50, with most of the unsaturationbeing contributed by the diene of formula (1).

Similarly, for a random copolymer of aryl-substituted olefins, aconjugated diene of formula (1) and a conjugated diene of formula (3),different from the conjugated diene of formula (1), the Iodine Numberbefore selective hydrogenation for the polymer is about 250 to about450. After selective hydrogenation, the Iodine Number for the polymer isabout 10 to about 100, most of it being contributed by the diene offormula (1).

The hydrogenated polymers may be vulcanized. The vulcanized randomcopolymers of this invention have elastomeric properties similar tothose of EPDM. The vulcanization rate of the polymers can be easily andinexpensively increased by increasing the content of the diene offormula (1), i.e., isoprene in the most preferred embodiment, in eitherembodiment of the random copolymers to from about 5 to about 20% bymole.

Star-Branched Polymers

The invention is also directed to star-branched block and randompolymers.

The star-branched block polymers are made from any combination of blocksI and B, A and D, or I, D and A all defined above, providing that eachfree end (i.e., the uncoupled end) of the star-branched polymer iseither an I or an A block in the star-branched block polymers made fromblocks I and B, A and D or I, D and A, respectively. The star-branchedI-B block polymers comprise about 0.5 to about 25%, preferably about 1to about 5% by wt. of the I blocks, and about 75 to about 99.5%,preferably about 95 to about 99% by wt. of the B blocks. Thestar-branched A-D block polymers comprise about 4 to about 60%,preferably about 8 to about 32% by wt. of the A blocks, and about 40 toabout 96%, preferably about 68 to about 92% by wt. of the D blocks. Thestar-branched I-D-A block polymers comprise about 1 to about 15,preferably about 2 to about 8% wt. of the blocks I, about 2 to about 30,preferably about 4 to about 16% wt. of the blocks A and about 55 toabout 97, preferably about 76 to about 94% wt. of the blocks D. Theblock A of this copolymer is either a block or a random copolymer ofabout 30 to about 70% by mole of at least one aryl-substituted olefinand about 30 to about 70% by mole of at least one conjugated diene offormula (1).

The star-branched block polymers are selectively hydrogenated in theselective hydrogenation process of this invention to such an extent thatblocks B or D contain substantially none of the original unsaturation,while each of the blocks I and A, respectively, retains a sufficientamount of the original unsaturation of the conjugated dienes present inthese blocks to cure the star-branched block polymers. Thus, for the I-Bstar-branched block polymer, after the selective hydrogenation reaction,the Iodine Number for the I blocks is about 10 to about 100%, preferablyabout 25 to about 100%, more preferably about 50 to about 100%, and mostpreferably about 100% of the Iodine Number prior to the selectivehydrogenation reaction, and for the B blocks it is about 0 to about 10%,preferably about 0 to about 0.5% of the Iodine Number prior to theselective hydrogenation reaction. Similarly, for the A-D star-branchedblock polymer, after the selective hydrogenation reaction, the IodineNumber for the A blocks is about 10 to about 100%, preferably about 25to about 100%, more preferably about 50 to about 100%, and mostpreferably about 100% of the Iodine Number prior to the selectivehydrogenation reaction, and for the D blocks it is about 0 to about 10%,preferably about 0 to about 0.5% of the Iodine Number prior to theselective hydrogenation reaction. Similarly, for the I-D-A star-branchedblock polymer, the Iodine Number for each of the I and A blocks afterthe selective hydrogenation is completed is about 10 to about 100%,preferably about 100% of the Iodine Number prior to the selectivehydrogenation reaction, and for the D blocks it is about 0 to about 10%,preferably about 0 to about 0.5%, and most preferably 0% of the IodineNumber prior to the selective hydrogenation reaction. Thus, in thisembodiment, the block D is also selectively hydrogenated in the samemanner as discussed above for the central blocks B and D of the otherembodiments of the invention.

The star-branched random polymers are made from any combination of atleast one diene of formula (1) and at least one diene of formula (3),different from the diene of formula (1), or from any combination of atleast one aryl-substituted olefin, at least one diene of formula (1) andat least one diene of formula (3), different from the diene of formula(1), all of which are the same as those discussed above. Thestar-branched random polymers of the dienes of formulae (1) and (3),which must be different from each other, comprise about 1 to about 25%,preferably about 1 to about 10% by wt. of the diene of formula (1) andabout 75 to about 99%, preferably about 90 to about 99% by wt. the dieneof formula (3). The star-branched random polymers of thearyl-substituted olefin and the dienes of formulae (1) and (3) compriseabout 0.3 to about 15% by mole of the aryl-substituted olefin, about 1to about 25%, preferably about 1 to about 10% by mole of the conjugateddiene of formula (1), and the remainder of the conjugated diene offormula (3). The star-branched random polymers are also selectivelyhydrogenated in the selective hydrogenation process of this invention tosuch an extent that the polymerized dienes of formula (3) containsubstantially none of the original unsaturation, while the polymerizeddienes of formula (1) retain a sufficient amount of the originalunsaturation to cure the star-branched random polymers. Thus, for thestar-branched random polymer of the conjugated diene of formula (1) anda different diene of formula (3), both identified above, the IodineNumber for the polymerized diene of formula (1), after the selectivehydrogenation reaction, is about 10 to about 100%, preferably about 25to about 100%, more preferably about 50 to about 100%, and mostpreferably about 100% of the Iodine Number prior to the selectivehydrogenation reaction, and for the polymerized diene of formula (3) itis about 0 to about 10%, preferably about 0 to about 0.5% of the IodineNumber prior to the selective hydrogenation reaction. Similarly, for thestar-branched random polymers made from at least one aryl-substitutedolefin, at least one diene of formula (1) and at least one diene offormula (3), the Iodine Number for the polymerized diene of formula (1),after the selective hydrogenation reaction, is about 10 to about 100%,preferably about 25 to about 100%, more preferably about 50 to about100%, and most preferably about 100% of the Iodine Number prior to theselective hydrogenation reaction, and for the polymerized diene offormula (3) it is about 0 to about 10%, preferably about 0 to about 0.5%of the Iodine Number prior to the selective hydrogenation reaction.

Blends Of Inventive Polymers With Other Materials

The block and random copolymers of this invention can, of course, beblended with any unsaturated elastomers, in which case the degree ofunsaturation of the copolymers of the invention can be adjusted so thatthe vulcanization rate of the two materials is substantially the same.Suitable elastomers which can be blended with the copolymers of thisinvention are liquid butyl, liquid polyisoprene, liquid polybutadiene(modified and unmodified), and liquid EPDM. Suitable solid rubbers withwhich the copolymers of this invention can be blended are, e.g., SBR,polyisoprene, polybutadiene, EPDM, butyl rubber and neoprene.

The block and random copolymers of this invention can, of course, becompounded with ingredients known to those skilled in the art, e.g.,fillers, such as silica, carbon black, extender oils, antioxidants,tackifying agents, vulcanizing agents and similar materials.

Polymerization Reaction

The block copolymers of this invention are polymerized by any knownblock polymerization processes, preferably by an anionic polymerizationprocess. Anionic polymerization is well known in the art and it isutilized in the production of a variety of commercial polymers. Anexcellent comprehensive review of the anionic polymerization processesappears in the text ADVANCES IN POLYMER SCIENCE 56, ANIONICPOLYMERIZATION, pp. 1-90, Springer-Verlag, Berlin, Heideberg, New York,Tokyo 1984 in a monograph entitled ANIONIC POLYMERIZATION OF NON-POLARMONOMERS INVOLVING LITHIUM, by R. N. Young, R. P. Quirk and L. J.Fetters, incorporated herein by reference. The anionic polymerizationprocess is conducted in the presence of a suitable anionic catalyst(also known as an initiator), such as n-butyl-lithium,sec-butyl-lithium, t-butyl-lithium, sodium naphthalide or cumylpotassium. The amount of the catalyst and the amount of the monomer inthe polymerization reaction dictate the molecular weight of the polymer.The polymerization reaction is conducted is solution using an inertsolvent as the polymerization medium, e.g., aliphatic hydrocarbons, suchas hexane, cyclohexane or heptane, or aromatic solvents, such as benzeneor toluene. In certain instances, inert polar solvents, such astetrahydrofuran, can be used alone as a solvent, or in a mixture with ahydrocarbon solvent.

The block polymerization process will be exemplified below for thepolymerization of the first embodiment of the invention, andspecifically for the preferred embodiment thereof, i.e., a triblock ofpolyisoprene-polybutadiene-polyisoprene. However, it will be apparent tothose skilled in the art that the same process principles can be usedfor the polymerization of all copolymers of the invention.

The process, when using a lithium-based catalyst, comprises forming asolution of the isoprene monomer in an inert hydrocarbon solvent, suchas cyclohexane, modified by the presence therein of one or more polarcompounds selected from the group consisting of ethers, thioethers andtertiary amines, e.g., tetrahydrofuran. The polar compounds arenecessary to control the microstructure of the butadiene center block,i.e., the content of the 1,2-structure thereof. The higher the contentof the polar compounds, the higher will be the content of the1,2-structure in these blocks. Since the presence of the polar compoundis not essential in the formation of the first polymer block with manyinitiators unless a high 3,4-structure content of the first block isdesired, it is not necessary to introduce the polar compound at thisstage, since it may be introduced just prior to or together with theaddition of the butadiene in the second polymerization stage. Examplesof polar compounds which may be used are dimethyl ether, diethyl ether,ethyl methyl ether, ethyl propyl ether, dioxane, diphenyl ether,tripropyl amine, tributyl amine, trimethyl amine, triethyl amine, andN-,N-,N'-,N'-tetramethyl ethylene diamine. Mixtures of the polarcompounds may also be used. The amount of the polar compound depends onthe type of the polar compound and the polymerization conditions as willbe apparent to those skilled in the art. The effect of polar compoundson the polybutadiene microstructure is detailed in ANTKOWIAK et al,TEMPERATURE AND CONCENTRATION EFFECTS ON POLAR-MODIFIED ALKYL LITHIUMPOLYMERIZATIONS AND COPOLYMERIZATIONS, JOURNAL OF POLYMER SCIENCE: PartA-l , Vol. 10, 1319-1334 (1972), incorporated herein by reference. Thepolar compounds also accelerate the rate of polymerization. If monomersother than 1,3-butadiene, e.g., pentadiene, are used to polymerize thecentral blocks B or D, polar compounds are not necessary to control themicrostructure because such monomers will inherently produce polymerswhich do not possess crystallinity after hydrogenation.

When the alkyl lithium-based initiator, a polar compound and an isoprenemonomer are combined in an inert solvent, polymerization of the isopreneproceeds to produce the first terminal block whose molecular weight isdetermined by the ratio of the isoprene to the initiator. The "living"polyisoprenyl anion formed in this first step is utilized as thecatalyst for further polymerization. At this time, butadiene monomer isintroduced into the system and block polymerization of the second blockproceeds, the presence of the polar compound now influencing the desireddegree of branching (1,2-structure) in the polybutadiene block. Theresulting product is a living diblock polymer having a terminal anionand a lithium counterion. The living diblock polymer serves as acatalyst for the growth of the final isoprene block, formed whenisoprene monomer is again added to the reaction vessel to produce thefinal polymer block, resulting in the formation of the I-B-I triblock.Upon completion of polymerization, the living anion, now present at theterminus of the triblock, is destroyed by the addition of a protondonor, such as methyl alcohol or acetic acid. The polymerizationreaction is usually conducted at a temperature of between 0° C. andabout 100° C., although higher temperatures can be used. Control of achosen reaction temperature is desirable since it can influence theeffectiveness of the polar compound additive in controlling the polymermicrostructure. The reaction temperature can be, for example, from 50°to 80° C. The reaction pressure is not critical and varies fromatmospheric to about 100 psig.

If the polar compounds are utilized prior to the polymerization of thefirst I segment, I blocks with high 3,4-unit content are formed. Ifpolar compounds (some of which can be Lewis bases) are added after theinitial I segment is prepared, the first I segment will possess a highpercentage of 1,4-microstructure (which is trisubstituted), and thesecond I segment will have a high percentage of 3,4-microstructure.

The production of triblock polymers having a high 1,4-unit content onboth of the terminal I blocks is also possible by the use of couplingtechniques illustrated below for apolyisoprene-polybutadiene-polyisoprene block copolymer: ##STR12##

The substitution of myrcene for the isoprene during the polymerizationof the I blocks insures the incorporation of a high proportion oftrisubstituted double bonds, even in the presence of polar compoundssince myrcene contains a pendant trisubstituted double bond which is notinvolved in the polymerization process. In a coupling process, similarto that described above, block polymers containing polyisoprene endblocks (or any other polymerized monomer suitable for use in the Iblock) having a high 3,4-microstructure content can be obtained byadding the polar compound prior to the isoprene (or another monomer)polymerization.

The use of the coupling technique for the production of triblockpolymers reduces the reaction time necessary for the completion ofpolymerization, as compared to sequential addition of isoprene, followedby butadiene, followed by isoprene. Such coupling techniques are wellknown and utilize coupling agents, such as esters, CO₂, iodine,dihaloalkanes, silicon tetrachloride, divinyl benzene, alkyltrichlorosilanes and dialkyl dichlorosilanes. The use of tri- ortetra-functional coupling agents, such as alkyl trichlorosilanes orsilicon tetrachloride, permits the formation of macromolecules having 1-or 2-main chain branches, respectively. The addition of divinyl benzeneas a coupling agent has been documented to produce molecules having upto 20 or more separately joined segments.

The use of some of the coupling agents provides a convenient means ofproducing star-branched block and random polymers. The star-branchedblock polymers are made from any combination of blocks I and B, A and Dor I, D and A, defined above, providing that each free end (i.e., theuncoupled end) of the star-branched polymer is either an I or an Ablock, respectively. The star-branched random polymers are made from anycombination of at least one diene of formula (1) and at least one dieneof formula (3), different from the diene of formula (1), or from atleast one aryl-substituted olefin, at least one diene of formula (1) andat least one diene of formula (3), different from the diene of formula(1). The molecular weight of the star-branched block and randomcopolymers will depend on the number of branches in each such copolymer,as will be apparent to those skilled in the art. Suitable couplingagents and reactions are disclosed in the following references which areincorporated herein by reference: U.S. Pat. Nos. 3,949,020; 3,594,452;3,598,887; 3,465,065; 3,078,254; 3,766,301; 3,632,682; 3,668,279; andGreat Britain patents 1,014,999; 1,074,276; 1,121,978.

The random copolymers of the invention are polymerized and/or coupled ina similar fashion, but all monomers, e.g., isoprene and butadiene, aremixed in a proper ratio prior to the reaction with the polarcompound-modified alkyl-lithium. In the random polymer preparation, ofcourse, only one stage is necessary.

Selective Hydrogenation

The selective hydrogenation reaction will also be described below usinga triblock of polyisoprene-polybutadiene-polyisoprene as an example.However, it will be apparent to those skilled in the art that anypolymers of this invention can be selectively hydrogenated in the samemanner.

The block copolymer is selectively hydrogenated to saturate the middle(polybutadiene) block of each of the triblocks. The method ofselectively hydrogenating the polybutadiene block is similar to that ofFalk, "Coordination Catalysts For The Selective Hydrogenation ofPolymeric Unsaturation", JOURNAL OF POLYMER SCIENCE: PART A-l , Volume9, 2617-2623 (1971), but it is conducted with a novel hydrogenationcatalyst and process used herein. Any other known selectivehydrogenation methods may also be used, as will be apparent to thoseskilled in the art, but it is preferred to use the method describedherein. In summary, the selective hydrogenation method preferably usedherein comprises contacting the previously-prepared block copolymer withhydrogen in the presence of the novel catalyst composition.

The novel hydrogenation catalyst composition and hydrogenation processare described in detail in previously cited Application Ser. No.07/466,1361. The hydrogenation catalyst composition is synthesized fromat least one transition metal compound and an organometallic reducingagent. Suitable transistion metal compounds are compounds of metals ofGroup IVb, Vb, VIb or VIII, preferably IVb or VIII of the Periodic Tableof the Elements, published in LANGE'S HANDBOOK OF CHEMISTRY (13thEdition, 1985) McGraw-Hill Book Company, New York (John A. Dean,editor). Non-limiting examples of such compounds are metal halides,e.g., titanium tetrachloride, vanadium tetrachloride; vanadiumoxytrichloride, titanium and vanadium alkoxides, wherein the alkoxidemoiety has a branched or unbranched alkyl radical of 1 to about 20carbon atoms, preferably 1 to about 6 carbon atoms. Preferred transitionmetal compounds are metal carboxylates or alkoxides of Group IVb or VIIIof the Periodic Table of the Elements, such as nickel (II)2-ethylhexanoate, titanium isopropoxide, cobalt (II) octoate, nickel(II) phenoxide and ferric acetylacetonate.

The organometallic reducing agent is any one or a combination of any ofthe materials commonly employed to activate Ziegler-Natta olefinpolymerization catalyst components containing at least one compound ofthe elements of Groups Ia, IIa, IIb, IIIa, or IVa of the Periodic Tableof the Elements. Examples of such reducing agents are metal alkyls,metal hydrides, alkyl metal hydrides, alkyl metal halides, and alkylmetal alkoxides, such as alkyllithium compounds, dialkylzinc compounds,trialkylboron compounds, trialkylaluminum compounds, alkylaluminumhalides and hydrides, and tetraalkylgemanium compounds. Mixtures of thereducing agents may also be employed. Specific examples of usefulreducing agents include n-butyllithium, diethylzinc, di-n-propylzinc,triethylboron, diethylaluminumethoxide, triethylaluminum,trimethylaluminum, triisoutylaluminum, tri-n-hexylaluminum,ethylaluminum dichloride, dibromide, and dihydride, isobutyl aluminumdichloride, dibromide, and dihyride, diethylaluminum chloride, bromide,and hydride, di-n-propylaluminum chloride, bromide, and hydridediisobutylaluminum chloride, bromide and hydride, tetramethylgermanium,and tetraethylgermanium. Organometallic reducing agents which arepreferred are Group IIIa metal alkyls and dialkyl metal halides having 1to about 20 carbon atoms per alkyl radical. More preferably, thereducing agent is a trialkylaluminum compound having 1 to about 6 carbonatoms per alkyl radical. Other reducing agents which can be used hereinare disclosed in Stevens et al, U.S. Pat. No. 3,787,384, column 4, line45 to column 5, line 12 and in Strobel et al, U.S. Pat. No. 4,148,754,column 4, line 56 to column 5, line 59, the entire contents of both ofwhich are incorporated herein by reference. Particularly preferredreducing agents are metal alkyl or hydride derivatives of a metalselected from Groups Ia, IIa and IIIa of the Periodic Table of theElements, such as n-butyl lithium, sec-butyl lithium, n-hexyl lithium,phenyl-lithium, triethylaluminum, tri-isobutylaluminum,trimethylaluminum, diethylaluminum hydride and dibutylmagnesium.

The molar ratio of the metal derived from the reducing agent to themetal derived from the transition metal compound will vary for theselected combinations of the reducing agent and the transition metalcompound, but in general it is about 1:1 to about 12:1, preferably about1.5:1 to about 8:1, more preferably about 2:1 to about 7:1 and mostpreferably about 2.5:1 to about 6:1. It will be apparent to thoseskilled in the art that the optimal ratios will vary depending upon thetransition metal and the organometallic agent used, e.g., for thetrialkylaluminum/nickel(II) systems, the preferred aluminum: nickelmolar ratio is about 2.5:1 to about 4:1, for thetrialkylaluminum/cobalt(II) systems, the preferred aluminum: cobaltmolar ratio is about 3:1 to about 4:1 and for thetrialkylaluminum/titanium(IV) alkoxides systems, the preferredaluminum:titanium molar ratio is about 3:1 to about 6:1.

The mode of addition and the ratio of the reducing agent to thetransition metal compound are important in the production of the novelhydrogenation catalyst having superior selectivity, efficiency andstability, as compared to prior art catalytic systems. During thesynthesis of the catalysts it is preferred to maintain the molar ratioof the reactants used to synthesize the catalyst substantially constant.This can be done either by the addition of the reducing agent, asrapidly as possible, to a solution of the transition metal compound, orby a substantially simultaneous addition of the separate streams of thereducing agent and the transition metal compound to a catalyst synthesisvessel in such a manner that the selected molar ratios of the metal ofthe reducing agent to the metal of the transition metal compound aremaintained substantially constant throughout substantially the entiretime of addition of the two compounds. The time required for theaddition must be such that excessive pressure and heat build up areavoided, i.e., the temperature should not exceed about 80° C. and thepressure should not exceed the safe pressure limit of the catalystsynthesis vessel.

In a preferred embodiment, the reducing agent and the transition metalcompound are added substantially simultaneously to the catalystsynthesis vessel in such a manner that the selected molar ratio of thereducing agent to the transistion metal compound is maintainedsubstantially constant during substantially the entire time of theaddition of the two compounds. This preferred embodiment permits thecontrol of the exothermic reaction so that the heat build up is notexcessive, and the rate of gas production during the catalyst synthesisis also not excessive-accordingly the gas build-up is relatively slow.In this embodiment, carried out with or without a solvent diluent, therate of addition of the catalyst components is adjusted to maintain thesynthesis reaction temperature at or below about 80° C., which promotesthe formation of the selective hydrogenation catalyst. Furthermore, theselected molar ratios of the metal of the reducing agent to the metal ofthe transition metal compound are maintained substantially constantthroughout the entire duration of the catalyst preparation when thesimultaneous mixing technique of this embodiment is employed.

In another embodiment, the catalyst is formed by the addition of thereducing agent to the transition metal compound. In this embodiment, thetiming and the order of addition of the two reactants is important toobtain the hydrogenation catalyst having superior selectivity,efficiency and stability. Thus, in this embodiment, it is important toadd the reducing agent to the transition metal compound in that order inas short a time period as practically possible. In this embodiment, thetime allotted for the addition of the reducing agent to the transitionmetal compound is critical for the production of the novel catalyst. Theterm "as short a time period as practically possible" means that thetime of addition is as rapid as possible, such that the reactiontemperature is not higher than about 80° C. and the reaction pressuredoes not exceed the safe pressure limit of the catalyst synthesisvessel. As will be apparent to those skilled in the art, that time willvary for each synthesis and will depend on such factors as the types ofthe reducing agents, the transition metal compounds and the solventsused in the synthesis, as well as the relative amounts thereof, and thetype of the catalyst synthesis vessel used. For purposes ofillustration, a solution of about 15 ml of triethylaluminum in hexaneshould be added to a solution of nickel(II) octoate in mineral spiritsin about 10-30 seconds. Generally, the addition of the reducing agent tothe transition metal compound should be carried out in about 5 seconds(sec) to about 5 minutes, depending on the quantities of the reagentsused. If the time period during which the reducing agent is added to thetransition metal compound is prolonged, e.g., more than 15 minutes, thesynthesized catalyst is less selective, less stable and may beheterogeneous.

In the embodiment wherein the reducing agent is added as rapidly aspossible to the transition metal compound, it is also important to addthe reducing agent to the transition metal compound in theaforementioned sequence to obtain the novel catalyst. The reversal ofthe addition sequence, i.e., the addition of the transition metalcompound to the reducing agent, or the respective solutions thereof, isdetrimental to the stability, selectivity, activity and homogeneity ofthe catalyst and is therefore undesirable.

In all embodiments of the hydrogenation catalyst synthesis, it ispreferred to use solutions of the reducing agent and the transitionmetal compound in suitable solvents, such as hydrocarbon solvents, e.g.,cyclohexane, hexane, pentane, heptane, benzene, toluene or mineral oils.The solvents used to prepare the solutions of the reducing agent and ofthe transition metal compound may be the same or different, but if theyare different, they must be compatible with each other so that thesolutions of the reducing agent and the transition metal compound arefully soluble in each other.

The hydrogenation process comprises contacting the unsaturated polymerto be hydrogenated with an amount of the catalyst solution containingabout 0.1 to about 0.5, preferably about 0.2 to about 0.3 mole percentof the transition metal based on moles of the polymer unsaturation. Thehydrogen partial pressure is about 5 psi to about several hundred psi,but preferably it is about 10 to about 100 psi. The temperature of thehydrogenation reaction mixture is about 25° to about 80° C., sincehigher temperatures may lead to catalyst deactivation. The length of thehydrogenation reaction may be as short as 30 minutes and, as will beapparent to those skilled in the art, depends to a great extent on theactual reaction conditions employed. The hydrogenation process may bemonitored by any conventional means, e.g., infra-red spectroscopy,hydrogen flow rate, total hydrogen consumption, or any combinationthereof.

Upon completion of the hydrogenation process, unreacted hydrogen iseither vented or consumed by the introduction of the appropriate amountof an unsaturated material, such as 1-hexene, which is converted to aninert hydrocarbon, e.g., hexane. Subsequently, the catalyst is removedfrom the resulting polymer solution by any suitable means, selecteddepending on the particular process and polymer. For a low molecularweight material, for example, catalyst residue removal may consist of atreatment of the solution with an oxidant, such as air, and subseqenttreatment with ammonia and optionally methanol in amounts equal to themolar amount of the metals (i.e., the sum of the transition metal andthe metal of the reducing agent) present in the hydrogenation catalystto yield the catalyst residues as a filterable precipitate, which isfiltered off. The solvent may then be removed by any conventionalmethods, such as vacuum stripping, to yield the product polymer as aclear, colorless fluid.

Alternatively, and in a preferred embodiment, upon completion of thehydrogenation reaction, the mixture is treated with ammonia in the molaramount about equal to that of the metals (i.e., the sum of thetransition metal and the metal of the reducing agent) and aqueoushydrogen peroxide, in the molar amount equal to about one half to aboutone, preferably one half, of the amount of the metals. Other levels ofthe ammonia and peroxide are also operative, but those specified aboveare particularly preferred. In this method, a precipitate forms, whichmay be filtered off as described above.

In yet another alternative method, the catalyst may be removed byextraction with an aqueous mineral acid, such as sulfuric, phosphoric orhydrochloric acid, followed by washing with distilled water. A smallamount of a material commonly used as an aid in removing transitionmetal-based catalysts, such as a commercially available high molecularweight diamine, e.g., Jeffamine D-2000 from Texaco, may be added to aidin phase separation and catalyst removal during the extractions. Theresultant polymer solution is then dried over a drying agent, such asmagnesium sulfate, separated from the drying agent and the solvent isthen separated by any conventional methods, such as vacuum stripping, toyield a polymer as a clear fluid. Other methods of polymer isolation,such as steam or alcohol flocculation, may be employed depending uponthe hydrogenated polymer properties.

Crosslinking And Functionalization Of The Terminal Blocks

In addition to acting as sites for vulcanization, the unsaturatedterminal blocks of the block polymers of this invention can bechemically modified to provide benefits obtained with similarmodifications of existing commercial materials, such as butyl rubber orEPDM. In some instances, the benefits obtained by a chemicalmodification of butyl rubber or EPDM may be magnified using theelastomers of out invention as a matrix instead of the butyl rubber orEPDM of similar molecular weight because of their intrinsically superiorelastomeric properties.

It is known that the halogenation of the unsaturation in butyl rubber(based upon isoprene monomer) prior to the vulcanization treatment,produces dramatic changes in vulcanization rate and provides greaterversatility in the choice of vulcanizing agents. Since the residualunsaturated groups in the first embodiment of out invention, present inthe I block, in the most preferred embodiment, are also based onisoprene monomer, the halogenation of the polymer of this embodimentprovides the same benefits, but with the retention of the greaterelongation characteristics inherent in the invention polymer. The samebenefits will be obtained with any other dienes which can be used toprepare the block I of this embodiment of the invention, and thereforeany polymers of this invention containing any such dienes can behalogenated in the same manner as the butyl rubber. Any other polymersof this invention containing the polymerized dienes of formula (1) orblocks I can also be halogenated in the same manner.

It is also known that the reaction of EPDM with maleic anhydride atelevated temperatures (e.g., about 150° C. to about 250° C.) producesmaleic modified EPDM which is used commercially as an impact modifier,particularly for Nylon. Similar modification of the polymers of anyembodiments of our invention occurs readily, since the residual isopreneunsaturation, primarily of the 3,4-type, illustrated above, is known tobe more reactive with maleic anhydride than are the internal bonds foundin EPDM. The resultant product provides improved impact properties whenblended with Nylon.

The above examples illustrate only some of the potentially valuablechemical modifications of the polymers of this invention. The liquidpolymers of this invention provide a means for a wide variety ofchemical modifications only at the ends of the molecule (i.e., at the Iblocks only), thereby presenting the opportunity to prepare materialspreviously impossible because of the lack of availability of suchpolymers. Some examples of well known chemical reactions which can beperformed on polymers of this invention are found in E. M. FETTES,CHEMICAL REACTIONS OF POLYMERS, High Polymers, Vol. 19, John Wiley, NewYork, 1964, incorporated herein by reference.

Until the instant invention, it has not been possible to produce liquidhydrocarbon elastomers having the capability of maintaining a largedistance between crosslinks (high M_(c)) after vulcanization. Ourinvention provides block hydrocarbon polymers capable of beingvulcanized to a perfect network with a distance between crosslinkssubstantially equivalent to the dimensions of the unvulcanizedelastomeric molecule. In addition to the expected improvements inelastomeric properties, the saturated main chain of the polymers of ourinvention provides a high degree of oxidative and thermal stability.Unique materials can also be obtained by chemical modifications of theblock polymers of this invention, since such modifications can becarried out selectively only at the unsaturated terminal ends of themolecules.

The crosslinking of the selectively hydrogenated block polymers of thisinvention is conducted in a conventional manner by contacting the blockcopolymer with a suitable crosslinking agent or a combination of suchagents. The crosslinking process produces a copolymer having uniformdistance between cross-links.

The block copolymers can also be functionalized by reacting the terminalblocks containing unsaturated groups with various reagents to producefunctional groups, such as hydroxyl, epoxy, sulfonic acid, mercapto,acrylate or carboxyl groups. Functionalization methods are well known inthe art. The functional groups can be used to produce both covalent andionic crosslinks.

The random copolymers may also be cross-linked or functionalized in thesame manner as the block copolymers.

The following Examples illustrate additional features of the invention.However, it will be apparent to those skilled in the art that thespecific reactants and reaction conditions used in the Examples do notlimit the scope of the invention.

In all of the following examples, the experimental work was performedwith dried reactors and equipment and under strictly anaerobicconditions. Extreme care must be used to exclude air, moisture and otherimpurities capable of interfering with the delicate chemical balanceinvolved in the synthesis of the polymers of this invention, as will beapparent to those skilled in the art.

EXAMPLE 1 Isoprene-Butadiene-Isoprene Triblock Polymer

Three hundred milliliters (ml) of purified, dried cyclohexane (99.5%,Phillips Petroleum) were introduced into a six-hundred milliliterstirred glass reactor. Air was removed from the reactor under vacuum andreplaced by dry nitrogen. The reactor was equipped with an air drivenstirrer, a pressure gauge, thermocouple, top surface inlet valve, diptube feeder with valve, heating-mantle and variable controller andcombination nitrogen/vacuum inlet with valve. Three ml of a 0.01Msolution of bipyridyl in cyclohexane, 7.3 ml (90 mmol) oftetrahydrofuran freshly distilled from benzophenone ketyl and 1.8 ml (18mmol) of purified isoprene were injected into the reactor. Thetemperature of the reactor and its contents was raised to 50° C. Thesolution was then titrated by addition of 1.6M butyl lithium until apersistent red color was obtained. Following this, 3.75 ml of 1.6M butyllithium was injected into the reactor in order to initiatepolymerization of the isoprene. The reaction was allowed to run for onehour, after which 47.5 g of purified butadiene were pressured into thereactor at a rate such that the reaction temperature did not exceed 70°C. After one hour, the reactor pressure had returned to its initiallevel and the formation of the second block of the copolymer wascompleted. Isoprene (1.8 ml, 18 mmol) was again injected into thereactor to allow for the formation of the third and final block of thetriblock polymer. After one hour, 0.35 ml of acetic acid (4.5 mmol) wereinjected into the reactor to quench the triblock living anion. The colorof the reaction mixture changed from a dark amber to colorlessimmediately. The mixture was cooled to room temperature, filteredthrough alumina/Celite, an anti-oxidant, Irganox 1076 from Ciba-Geigy(100 ppm based on dry polymer) was added and solvent was removed underreduced pressure to yield a triblock polymer of about 8400 molecularweight as a clear, colorless, viscous fluid. Infra-red analysis (FourierTransform) showed the butadiene center block to possess 55% (1,2)- and45% of (1,4)-microstructure.

EXAMPLE II Isoprene-Butadiene-Isoprene Triblock Polymer

This example is similar to that of Example 1, but the scale wasincreased to utilize a one gallon stainless steel pressure reactor.

1500 grams of purified, dried cyclohexane (99.5%, Phillips Petroleum)were introduced into a one gallon stirred stainless steel reactor. Thereactor was equipped with a stirrer, pressure gauge, thermocouple, topsurface inlet, dip tube feeder with valve, variably controlled heaterand heat exchange coil. Following the addition of the solvent, 50 ml(0.614 mol) of tetrahydrofuran freshly distilled from benzophenoneketyl, 43.3 ml (0.433 mol) of purified isoprene and an additional 80 gof cyclohexane were pressured into the reactor. The temperature of thereactor and its contents was raised to 50° C. Butyl lithium (61.2 ml of1.5M solution, 91.8 mmol) was pressured into the reactor in order totitrate impurities and initiate polymerization of the isoprene. Thereaction was allowed to run for one hour, after which 1100 ml ofpurified butadiene (12.65 mol) were pumped into the reactor at a ratesuch that the reaction temperature did not exceed 60° C. Cooling waterwas passed through the heat exchanger during this process to aid in thecontrol of temperature. The butadiene feed was complete within thirtyminutes. One hour later, the formation of the second block of thecopolymer was complete and isoprene (43.3 ml, 0.433 mol) in 50 g ofcyclohexane was again pressured into the reactor to allow for theformation of the third and final block of the triblock polymer. Afterone hour, the reaction mixture was cooled and discharged into a vesselcontaining 5.2 ml of acetic acid (90.8 mmol) to quench the triblockliving anion. The mixture was filtered through alumina/Celite, ananti-oxidant (100 ppm based on dry polymer) was added and the solventwas removed under reduced pressure to yield a triblock polymer of about8200 molecular weight as a clear, colorless, viscous fluid. Infra-redanalysis (Fourier Transform) showed the butadiene center block topossess 56% (1,2)- and 44% of (1,4)-microstructure.

EXAMPLE III Viscosity as a Function of Molecular Weight

This example illustrates the relationship between the molecular weightof the triblock polymers prepared in the manner substantially the sameas that of Examples I and II and their resulting bulk viscosities.

As is apparent from the data of FIG. 1, a linear relationship existsbetween the molecular weight of the unhydrogenatedisoprene-butadiene-isoprene polymers prepared as in Examples I and IIand the log of their room temperature bulk viscosities as measured usinga Brookfield Engineering LVT viscometer operating at, for example, 0.6rpm with spindle number 5.

EXAMPLE IV Isoprene/Styrene-Butadiene-Isoprene/Styrene Triblock Polymer

This example illustrates the preparation of a triblock polymer whereinthe terminal blocks consist of isoprene-styrene copolymers.Incorporation of levels of styrene approximately comparable to those ofisoprene into the end blocks is beneficial with certain methods ofvulcanizing the final selectively hydrogenated triblock.

1400 grams of purified, dried cyclohexane (99.5%, Phillips Petroleulm)were introduced into a one gallon stirred stainless steel reactor. Thereactor was equipped with a stirrer, pressure gauge, thermocouple, topsurface inlet, dip tube feeder with valve, variably controlled heaterand heat exchange coil. Following the addition of the solvent, 88 ml(1.08 mol) of tetrahydrofuran fresly distilled from benzophenone ketyl,21.8 ml (0.218 mol) of purified isoprene, 41.5 ml of purified styrene(0.362 mol) and an additional 50 g of cyclohexane were pressured intothe reactor. The temperature of the reactor and its contents was raisedto 50° C. Butyl lithium (47.0 ml of 1.6M solution, 75.2 mmol) was thenpressured into the reactor in order to titrate impurities and initiatepolymerization of the isoprene. The reaction was allowed to run for onehour, after which 800 ml of purified butadiene (9.20 mol) were pumpedinto the reactor at a rate such that the reaction temperature did notexceed 60° C. Cooling water was passed through the heat exchanger duringthis process to aid in the control of temperature. The butadiene feedwas complete within thirty minutes. One hour later, the formation of thesecond block of the copolymer was complete and a mixture of isoprene(21.8 ml, 0.218 mol) and styrene (41.5 ml, 0.362 mol) in 50 g ofcyclohexane was again pressured into the reactor to allow for theformation of the third and final block of the triblock polymer. Afterone hour, the reaction mixture was cooled and discharged into a vesselcontaining 4.3 ml of acetic acid (75.2 mmol) to quench the triblockliving anion. The mixture was filtered through alumina/Celite, ananti-oxidant (100 ppm based on dry polymer) was added and solvent wasremoved under reduced pressure to yield a triblock polymer of about 8000molecular weight as a clear, colorless viscous fluid. Infra-red analysis(Fourier Transform) showed the butadiene center block to possess 57%(1,2)- and 43% (1,4)-microstructure.

EXAMPLE V Isoprene-Butadiene Random Copolymer

This example illustrates the preparation of a random copolymerconsisting of isoprene and butadiene wherein the isoprene proportion iscompletely analogous to that of the triblock material of Example I.

800 ml of purified, dried cyclohexane (99.5%, Phillips Petroleum) wereintroduced into a two liter stirred glass reactor. The reactor waspurged several times with dry nitrogen. The reactor was equipped with anair driven stirrer, a pressure gauge, thermocouple, top surface inletvalve, dip tube feeder with valve, heat exchange coil and nitrogen inletwith valve. 5 ml of a 0.01M solution of bipyridyl in cyclohexane and16.1 ml (198 mmol) of tetrahydrofuran freshly distilled formbenzophenone ketyl were injected into the reactor. The reactor contentswere titrated with 1.6M butyl lithium to a persistent red endpoint. Thetemperature of the reactor and its contents was raised to 50° C. and 8.3ml of 1.6M butyl lithium (13.3 mmol) were added. A mixture of 13.3 ml ofisoprene (0.133 mol) and 90.9 g of purified butadiene (1.68 mol) wasthen pressured into the reactor at a rate that allowed for maintaining atemperature of between 50° and 60° C. The feed was completed in about 20minutes, after which the reaction was allowed to proceed for anadditional hour. The contents were cooled and discharged into a vesselcontaining 0.53 ml of methanol (13 mmol) to quench the copolymer livinganion. The color of the reaction mixture changed from a dark amber tocolorless immediately. The mixture was filtered through alumina/Celite,an anti-oxidant (100 ppm based on dry polymer) was added and solvent wasremoved under reduced pressure to yield a random copolymer of about 7500molecular weight as a clear, colorless, viscous fluid. Infra-redanalysis (Fourier Transform) showed the butadiene portion to possess 60%(1,2)- and 40% (1,4)-microstructure. In general, the infra-red spectrumwas essentially indistinguishable from that of the triblock material ofExamples I and II.

EXAMPLE VI-COMPARATIVE Low Molecular Weight Polybutadiene

This example illustrates the preparation of a low molecular weightpolybutadiene in a manner completely analogous to that of the randomcopolymer of Example V.

800 ml of purified, dried cyclohexane (99.5%, Phillips Petroleum) wereintroduced into a two liter stirred glass reactor. The reactor waspurged several times with dry nitrogen. The reactor was equipped with anair driven stirrer, a pressure gauge, thermocouple, top surface inletvalve, dip tube feeder with valve, heat exchange coil and nitrogen inletwith valve. 5 ml of a 0.01M solution of bipyridyl in cyclohexane and16.1 ml (198 mmol) of tetrahydrofuran freshly distilled frombenzophenone ketyl were injected into the reactor. The reactor contentswere titrated with 1.6M butyl lithium to a persistent red endpoint. Thetemperature of the reactor and its contents was raised to 50° C. and 8.3ml of 1.6M butyl lithium (13.3 mmol) were added. Purified butadiene (100g, 1.85 mol) was then pressured into the reactor at a rate that allowedfor maintaining a temperature of between 50° and 60° C. The feed wascomplete in about 20 minutes, after which the reaction was allowed toproceed for an additional hour. The contents were cooled and dischargedinto a vessel containing 0.55 ml of methanol (13.5 mmol) to quench thepolybutadienyl living anion. The color of the reaction mixture changedfrom a dark amber to colorless immediately. The mixture was filteredthrough alumina/Celite, an anti-oxidant (100 ppm based on dry polymer)was added and solvent was removed under reduced pressure to yieldpolybutadiene of about 7500 molecular weight as a clear, colorless,viscous fluid. Infra-red analysis (Fourier Transform) showed thepolybutadiene to possess 45% (1,2)- and 55% (1,4)-microstructure. Ingeneral, the infra-red spectrum was essentially indistinguishable fromthat of the triblock material of Examples I and II.

EXAMPLE VII Hydrogenation Catalyst Preparation

This example illustrates the preparation of the selective hydrogenationcatalyst used in subsequent examples.

In a clean, dry pressure bottle equipped with a magnetic stir bar, wereplaced 77.88 ml of pure, dry cyclohexane and 7.34 g of nickel (II)octoate (8% in mineral spirits, Mooney Chemical). The bottle was sealedwith a septum and bottle cap, evacuated and refilled with dry nitrogen.The process was repeated several times. The mixture was then stirredvigourously and 14.40 ml of 1.73M triethylaluminum was added via syringeas quickly as practicable (about 15 seconds). Periodically, pressure wasvented by means of a needle fitted with a valve. There was no evidenceof heterogeneity in the final black reaction mixture. The catalystsolution nickel concentration was 0.1M and the molar ratio of aluminumto nickel was 3.6.

EXAMPLE VIII Hydrogenation of Isoprene-Butadiene-Isoprene BlockCopolymer

This example illustrates the selective hydrogenation of the centralpolybutadiene block of an isoprene-butadiene-isoprene triblock polymer.

250 ml of cyclohexane in which was dissolved 23 g of triblock polymermade in the manner similar to that of Example I were purged of air byevacuation followed by the introduction of dry nitrogen. This amount ofpolymer contained 0.403 moles of polybutadiene unsaturation. To thepolymer solution was added 25 ml of a hydrogenation catalyst solutioncomprised of triethylaluminum and nickel (II) octoate in a 3.6:1 ratiowith a nickel concentration of 0.1M in cyclohexane. The resultingmixture was placed in a Parr hydrogenation apparatus and pressured to 50psig hydrogen. The apparatus was vented and the process repeated twicemore, after which the pressure was maintained at 50 psig of hydrogen.The temperature was raised to 50° C. and the mixture was agitatedvigorously. Hydrogen was fed on demand in order to maintain 50 psig inthe vessel and the flow rate was monitored by means of a mass flowmeter. The progress of the hydrogenation process was monitored both byFourier Transform infra-red spectroscopy and hydrogen flow rate. Aninfra-red spectrum obtained at the start of the process displayed thepresence of primarily the butadiene unsaturation (peaks at 995, 968 and910 wavenumbers). After thirty minutes, butadiene vinyl unsaturation(peaks at 995 and 910 wavenumbers) was gone, the trans-(1,4)-butadienewas significantly reduced (968 wavenumbers) and the isoprene vinylidene(888 wavenumbers) was very much in evidence. After ninety minutes, onlythe isoprene unsaturation remained. This final point corresponds to zerohydrogen flow. Upon completion of the selective hydrogenation process,the vessel was vented and the black reaction mixture was stirred in airwith ammonium hydroxide and methanol stoichiometrically equivalent tothe total catalyst metal content (11.5 mmol, 0.7 ml concentrated ammoniaand 0.5 ml methanol). Within several hours, the mixture had changed to adark green color indicative of oxidized nickel. The mixture was filteredthrough alumina/Celite and an anti-oxidant was added in the amountequivalent to 100 ppm based on the dry polymer weight. Solvent was thenremoved under reduced pressure to yield the product as a clear,colorless, viscous fluid.

EXAMPLE IX Viscosity as a Function of Molecular Weight of HydrogenatedTriblock Copolymer

This example illustrates the relationship between the molecular weightof the selectively hydrogenated triblock polymers prepared in the mannerof Example VIII and their resulting bulk viscosities.

As is apparent in FIG. 2, a monotonic increase in room temperature bulkviscosity is observed as the molecular weight of the selectivelyhydrogenated triblock polymers is increased. In all cases, a BrookfieldEngineering LVT viscometer operating at, for example 0.6 rmp withspindle number 5 was used. Surprisingly, however, even at a molecularweight of ten thousand g/mol (Mn=Mw) the bulk viscosity does not exceedone million centipoises.

    ______________________________________                                        Triblock Molecular Weight                                                     2000      5000    6500        7500  10000                                     Bulk Viscosity (cps)                                                          8500     54700   424000      745000                                                                              976000                                     ______________________________________                                    

EXAMPLE X Hydrogenation of Isoprene/Styrene-Butadiene-Isoprene/StyreneTriblock Polymer

This example illustrates the selective hydrogenation of the centralpolybutadiene block of a triblock polymer wherein the terminal blocksconsist of isoprene-styrene copolymers.

The process was carried out in a manner completely analogous to that ofExample VIII to give a material in which only the isoprene unsaturationremained as evidenced by Fourier Transform infra-red spectroscopy.

EXAMPLE XI Hydrogenation of Random Isoprene-Butadiene Copolymer

This example illustrates the selective hydrogenation of the butadieneportion of a random copolymer of isoprene-butadiene prepared as inExample V.

The process was carried out in a manner completely analogous to that ofExample VIII to give a material in which only the isoprene unsaturationremained as evidenced by Fourier Transform infra-red spectroscopy.

EXAMPLE XII Hydrogenation of Low MW Polybutadiene

This example illustrates the selective partial hydrogenation of a lowmolecular weight polybutadiene prepared as in Example VI.

250 ml of cyclohexane in which was dissolved 30 g of polybutadieneprepared in Example VI were purged of air by evacuation followed byintroduction of dry nitrogen. This amount of polymer contained 0.556moles of unsaturation. To the polymer solution was added 15 ml of ahydrogenation catalyst solution analogous to that of Example VIII. Theresulting mixture was placed in a Parr hydrogenation apparatus andpressured to 50 psig hydrogen. The apparatus was vented and the processrepeated twice more, after which the pressure was maintained at 50 psigof hydrogen. The mixture was agitated vigorously and hydrogen was fed ondemand in order to maintain 50 psig pressure in the vessel. The progressof the hydrogenation process was monitored both by Fourier Transforminfra-red spectroscopy and hydrogen flow rate as indicated by a massflow meter. After twenty-five minutes, the hydrogen flow rate hadreached a level that indicated that most of the hydrogenation wascomplete. The process was halted and an infra-red spectrum showed onlythe presence of trans-(1,4)-polybutadiene unsaturation at a levelcomparable to that of isoprene unsaturation levels of selectivelyhydrogenated isoprene-butadiene-isoprene triblock polymers prepared asin Example VIII. The vessel was vented and the black reaction mixturewas stirred in air with ammonium hydroxide and methanolstoichoimetrically equivalent to the total catalyst metal content (6.9mmol, 0.4 ml concentrated ammonia and 0.3 ml methanol). Within severalhours the mixture had changed to a dark green color indicative ofoxidized nickel. The mixture was filtered through alumina/Celite and ananti-oxidant was added in an amount equivalent to 100 ppm based on drypolymer weight. The solvent was then removed under reduced pressure toyield the product which was a clear, colorless, viscous fluid.

EXAMPLE XIII Vulcanization of Hydrogenated Isoprene-Butadiene-IsopreneTriblock

This example illustrates the low temperature vulcanization (cure) of aselectively hydrogenated low molecular weightisoprene-butadiene-isoprene triblock polymer into a solid rubber usingthe quinone dioxime (GMF) cure.

The ingredients listed below were mixed thoroughly without heatingeither by hand or in a Brabender mixer to a uniform consistency. Theresulting paste was placed in a Teflon mold with dimensions of3"×3"×0.25" and cured in a Carver press for one hour at 50° C. and 6000psi pressure. Subsequently, the sample was removed from the mold andallowed to age for a period of at least three hours at 50° C. Theresulting solid rubber was non-tacky, elastic and displayed tensilestrength and elongation values at break of 350 psi and 200%respectively.

    ______________________________________                                        Mix Recipe         Parts                                                      ______________________________________                                        Triblock Polymer   100.0                                                      GMF (quinone dioxime)                                                                            11.0                                                       N-Chlorosuccinimide                                                                              17.2                                                       Zinc Oxide          7.6                                                       ______________________________________                                    

EXAMPLE XIV Rubber Properties as Function of Molecular Weight

This example illustrates the relationship between selectivelyhydrogenated triblock polymer molecular weight and final cured rubberproperties. The cure method as described in Example XIII was employedwith the addition of silica as an inert filler at a level of 50 parts tocure triblock polymers of isoprene-butadiene-isoprene prepared in themanner substantially the same as that of Example VII. The results aresummarized below and in FIG. 3.

As shown in FIG. 3, for the range of molecular weights examined (2,000to 10,000 g/mol), a maximum percent elongation value of 180% at breakwas observed for the 7,500 molecular weight selectively hydrogenatedtriblock polymer. The 10,000 molecular weight material displayed asimilar but slightly inferior value and the materials of lower molecularweight were clearly inferior with respect to cured properties. Forcomparison, the uncured triblock bulk viscosities are included in thedata.

    ______________________________________                                                  Parts                                                               ______________________________________                                        Mix Recipe: 100.0                                                             GMF         14.4                                                              N-Chloro-   22.4                                                              succinimide                                                                   Zinc Oxide  10.0                                                              Silica      50.0                                                              Physical Properties:                                                          Molecular Weight                                                                          2,000     5,000   6,500                                                                               7,500                                                                               10,000                              Bulk Viscosity (cps)                                                                      8,500    54,700  424,000                                                                             745,000                                                                             976,000                              % Elongation                                                                              20          75      100                                                                                 180                                                                                 165                               ______________________________________                                    

EXAMPLE XV Cured Rubber Properties as Function of Hydrogenated PolymerMW

This example illustrates the relationship between selectivelyhydrogenated triblock polymer molecular weight and final cured rubberproperties. The cure method as described in Example XIII was employedwith the adjustment of the curative levels to the isoprene unsaturationlevels for the appropriate molecular weight. The triblock polymers weremade from isoprene-butadiene-isoprene in the manner substantially thesame as that of Example VII. The results are summarized below and inFIG. 4.

As shown in FIG. 4, for the range of molecular weights examined (5,000to 10,000 g/mol), a maximum percent elongation value of greater than250% at break was observed for the materials above 7,500 molecularweight. The 10,000 molecular weight material displayed slightly betterelongation and the lower molecular weight polymers were clearly inferiorwith elongations at break of 100% and less.

    ______________________________________                                                   Molecular Weight                                                              5,000  6,500    7,500    10,000                                    ______________________________________                                        Mix Recipe:                                                                   Polymer      100.0    100.0    100.0  100.0                                   GMF          19.6     14.4     12.4   9.4                                     N-Chlorosuccinimide                                                                        25.2     22.4     19.4   14.6                                    Zinc Oxide   13.2     10.0      8.6   6.6                                     Physical Properties                                                           % Elongation 65       109      245    262                                     ______________________________________                                    

EXAMPLE XVI Star Branched Polymers

This example illustrates the preparation of anisoprene-butadiene-isoprene triblock living polymer that is subsequentlycoupled to yield branched materials containing two arms (a pentablock),three arms (Y-shaped), four arms (plus-shaped), etc. The method issimilar to that of Example I, but a fractional equivalent of quenchingreagent containing multiple sites to react with the polymer livinganion, such as silicon tetrachloride, was employed instead of aceticacid. For example, one-fourth of an equivalent of silicon tetrachloridewas used based on the amount of n-butyl lithium employed in thepolymerization.

The polymers prepared were obtained as colorless fluids with viscositiescomparable to the parent triblock polymer, i.e., the materials are stillliquids despite their relatively high molecular weights.

    ______________________________________                                                                     Bulk Viscosity                                   Quenching Reagent                                                                          Polymer Obtained                                                                              (cps)                                            ______________________________________                                        Trichlorosilane                                                                            Y-shaped, 25500 g/mol                                                                         569,000                                          Silicon Tetrachloride                                                                      +-shaped, 34000 g/mol                                                                         254,000                                          Unhydrogenated 8500 MW Triblock from Example                                                           178,000                                              Example III:                                                                  ______________________________________                                    

EXAMPLE XVII Star Branched Polymers

This example illustrates the preparation of an isoprene-butadienediblock living polymer that is subsequently coupled to yield branchedmaterials containing two arms (a triblock), three arms (Y-shaped), fourarms (plus-shaped), etc. The method is similar to that of Example XVI,but quenching of the living anion is performed after the formation ofthe second polymer block, i.e., the polyisoprene-butadienyl anion. Thematerial obtained had isoprene blocks only on the ends of the individualbranches and not at their junction.

EXAMPLE XVIII Hydrogenation of Star-Branched Polymers

This example illustrates the selective hydrogenation of the butadieneblocks of the branched materials of Examples XVI and XVII.

The process was carried out in a manner analogous to that of ExampleVIII to give materials in which only the isoprene unsaturation remainedas evidenced by Fourier Transform infra-red spectroscopy.

EXAMPLE XIX Properties of Hydrogenated Polymers

This example illustrates the relationship between the degree ofbranching of selectively hydrogenated isoprene-butadiene-isoprenepolymers with approximately the same distance between crosslinks, M_(c)of 8500, and the molecular weight and final cured rubber properties. Thecure method as described in Example XIII was employed. The branchedmaterials cured significantly faster at the same curatives level torubbers of somewhat superior performance. All three samples of thisExample were prepared from the same mix recipe summarized below.

    ______________________________________                                                     Parts                                                            ______________________________________                                        Mix Recipe:                                                                   Triblock Polymer                                                                               100.0                                                        GMF              11.0                                                         N-Chlorosuccinimide                                                                            17.2                                                         Zinc Oxide        7.6                                                         Uncured        8400      25500    34000                                       Molecular Weight                                                              Cured Physical                                                                Properties                                                                    Approximate M.sub.c                                                                          8400      8500     8500                                        % Elongation   202       201      266                                         Tensile (psi)  329       408      421                                         Shore A Hardness                                                                              64        62       58                                         ______________________________________                                    

It will be apparent to those skilled in the art that the specificembodiments discussed above can be successfully repeated withingredients equivalent to those generically or specifically set forthabove and under variable process conditions.

From the foregoing specification, one skilled in the art can readilyascertain the essential features of this invention and without departingfrom the spirit and scope thereof can adapt it to various diverseapplications.

We claim:
 1. A liquid block copolymer comprising at least threealternating blocks

    (I).sub.x -(B).sub.y -(I).sub.x

wherein: I is a block of at least one polymerized conjugated dienehaving at least five (5) carbon atoms and the following formula##STR13## wherein R¹ -R⁶ are each hydrogen or a hydrocarbyl group,provided that at least one of R¹ -R⁶ is a hydrocarbyl group and providedthat the structure of the residual double bond in the polymerized blockI has the following formula ##STR14## wherein R^(I), R^(II), R^(III) andR^(IV) are each hydrogen or a hydrocarbyl group, provided that eitherboth R^(I) and R^(II) are hydrocarbyl groups or both R^(III) and R^(IV)are hydrocarbyl groups; B is a block of a polymer of at least oneconjugated diene, different from that used to polymerize the block I,having at least four (4) carbon atoms and the following formula##STR15## wherein R⁷ -R¹² are each hydrogen or a hydrocarbyl group,provided that the structure of the residual double bond in thepolymerized block B has the following formula ##STR16## wherein R^(a),R^(b), R^(c) and R^(d) are each hydrogen (H) or a hydrocarbyl group,provided that one of R^(a) or R^(b) is hydrogen, one of R^(c) or R^(d)is hydrogen, and at least one of R^(a), R^(b), R^(c) or R^(d) is ahydrocarbyl group; x is at least 1, and y is at least 25; saidpolymerized block B containing at least about 25 wt. % of 1,2-units ifit is a polymer of predominantly 1,3-butadiene; said copolymer beingselectively hydrogenated so that each of the blocks B is substantiallycompletely hydrogenated and thereby contains substantially none of theoriginal unsaturation, while each of the blocks I retains a sufficientamount of its original unsaturation to vulcanize said copolymer.
 2. Acopolymer of claim 1 having molecular weight of at least about 2,000. 3.A copolymer of claim 1 having molecular weight of about 5,000 to about10,000.
 4. A copolymer of claim 3 wherein x is 1 to 30 and y is 30 to275.
 5. A copolymer of claim 4 wherein x is 2 to 20 and y is 85 to 225.6. A copolymer of claim 5 wherein x is 3 to 10 and y is 130 to
 200. 7. Acopolymer of claim 6 wherein, after the hydrogenation reaction, theIodine Number for the I blocks is about 20 to about 100% of the IodineNumber prior to the hydrogenation reaction.
 8. A copolymer of claim 7wherein, after the hydrogenation reaction, the Iodine Number for the Iblocks is about 100% of the Iodine Number prior to the hydrogenationreaction.
 9. A copolymer of claim 8 wherein, after the hydrogenationreaction, the Iodine Number for the B blocks is about 0 to about 10% ofthe Iodine Number prior to the hydrogenation reaction.
 10. A copolymerof claim 9 wherein, after the hydrogenation reaction, the Iodine Numberfor the B blocks is about 0 to about 0.2% of the Iodine Number prior tothe hydrogenation reaction.
 11. A copolymer of claim 10 wherein thediene of formula (1) is isoprene, 2,3-dimethyl-butadiene,2-methyl-1,3-pentadiene, myrcene, 2-methyl-1,3-pentadiene,3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene,2-phenyl-1,3-butadiene, 2-phenyl-1,3-pentadiene,3-phenyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene,4-methyl-1,3-pentadiene, 2-hexyl-1,3-butadiene, 3-methyl-1,3-hexadiene,2-benzyl-1,3-butadiene, 2-p-tolyl-1,3-butadiene or mixtures thereof. 12.A copolymer of claim 11 wherein the diene of formula (1) is isoprene,myrcene or 2-methyl-1,3-pentadiene.
 13. A copolymer of claim 12 whereinthe diene of formula (1) is isoprene.
 14. A copolymer of claim 13wherein the diene of formula (3) is 1,3-butadiene, 1,3-pentadiene,2,4-hexadiene, 1,3-hexadiene, 1,3-heptadiene, 2,4-heptadiene,1,3-octadiene, 2,4-octadiene, 3,5-octadiene, 1,3-nonadiene,2,4-nonadiene, 3,5-nonadiene, 1,3-decadiene, 2,4-decadiene,3,5-decadiene or mixtures thereof.
 15. A copolymer of claim 14 whereinthe diene of formula (3) is 1,3-butadiene, 1,3-pentadiene, 2,4-hexadieneor 1,3-hexadiene.
 16. A copolymer of claim 15 wherein the diene offormula (3) is 1,3-butadiene.
 17. A copolymer of claim 16 wherein eachof the B blocks, prior to the selective hydrogenation reaction, is amixture of 1,4- and 1,2-units.
 18. A copolymer of claim 17 wherein eachof the B blocks, prior to the selective hydrogenation reaction, has atleast about 25% wt. of the 1,2-units.
 19. A copolymer of claim 18wherein each of the B blocks, prior to the selective hydrogenationreaction, has about 30 to about 90% wt. of the 1,2-units.
 20. Acopolymer of claim 19 wherein each of the B blocks has about 45 to about65% wt. of the 1,2-units.
 21. A halogenated polymer produced by a methodcomprising halogenating the polymer of claim
 1. 22. A maleated polymerproduced by a method comprising contacting the polymer of claim 1 withmaleic anhydride.
 23. A vulcanized polymer produced by vulcanizing theselectively hydrogenated liquid block copolymer of claim
 1. 24. A liquidblock copolymer comprising at least three (3) alternating blocks bondedto each other, the terminal blocks of said alternating blocks being ablock or random polymer of at least one polymerized hydrocarbonconjugated diene (I) monomer containing at least five (5) carbon atoms,with at least one carbon atom of each pair of residual double-bondedcarbon atoms of polymerized conjugated diene (I) units beingadditionally single-bonded to two carbon atoms, or a copolymer of atleast one diene (I) and at least one aryl-substituted olefin, the blocksbetween said polymerized diene (I) containing blocks being a polymer ofat least one polymerized hydrocarbon conjugated diene (B), which isdifferent from conjugated diene (I) and contains at least four (4)carbon atoms, with each residual double-bonded carbon atom ofpolymerized conjugated diene (B) units being additionally bonded to ahydrogen atom, said block copolymer being selectively hydrogenated sothat said polymerized conjugated diene (B) units are substantiallycompletely hydrogenated and contain substantially none of the originalunsaturation, while said polymerized conjugated diene (I) units retainsufficient amount of their original unsaturation to vulcanize saidcopolymer.
 25. A halogenated polymer produced by a method comprisinghalogenating the block polymer of claim
 24. 26. A maleated polymerproduced by a method comprising contacting the block polymer of claim 24with maleic anhydride.